London, Salisbury, and looking for suggestions to fill 2 more days

Do you really need to hire a car? Much of what you are thinking of doing can be done by public transport and the roads in the areas mentioned can be really busy.

I would consider doing your trip in this order - so as to place you in London ready for the short train ride to Gatwick for homeward flight. Stay in hotel near Gatwick overnight. Next day - train to Salisbury and stay a couple of nights. During this time - take shuttle bus to Stonehenge.http://www.thestonehengetour.info/timetable

Then - either take train to Bath for a day trip returning to Salisbury (add extra night accommodation) OR up sticks and take a train to Bath and stay a couple of nights before returning to London. (Glastonbury is not worth a visit).

For train schedules & fares :> www.nationalrail.co.uk (On many routes, cheaper fares for specific trains appear about 11 weeks out. These gradually increase nearer date).

Click this link and take a look at the roads:> https://www.google.co.uk/maps/@51.1365774,-1.2370212,95433m/data=!3m1!1e3!5m1!1e1
If you do hire a car, your son may like a diversion into this place - which is between Salisbury/Stonehenge & Bath:>https://www.longleat.co.uk

James, thank you for the links, I will check them out. I appreciate your reasoning to do London at the end of our trip, but with our flights and Stone Henge Inner Circle already booked, I want to keep London at the beginning of our trip so we have more time there.

Depending on where we go after Stone Henge, we may not need a car. I've considered going elsewhere in the countryside after Stone Henge (where a rental car may be needed), or staying in Salisbury for the last 2 days (but I'm not sure if that's too much time in that area?).

If you did have a car and were staying longer in Salisbury, then you could take a day trip down to the Dorset coast (going SW from Salisbury via A354 to Blandford Forum and then go via Beer Regis) to Lulworth Cove - and Durdle Dor = a sea arch just to the west. (See map link for where this is). However, you are going at the end of March and it can be quite chilly - though I have seen people sunbathing in parks at this time of year .http://www.lulworthonline.co.uk

The National Trust property at Mottisfont is not too far E of Salisbury and this could be combined with Winchester (where parking can be difficult).

If you have a car, this place has lodges in woodland and is midway between Salisbury/Stonehenge & Bath - trouble is that you may be paying for facilities that you do not want as you wish to see places.http://www.centerparcs.co.uk/villages/longleat/index.jsp

A few thoughts.....

1. March weather. I've never been to the UK in March so no personal experience but I'd check websites that provide info on what to possibly expect temp and rain wise. You've already mentioned a concern about driving on the left so can't imagine you'd like to do it in a downpour.

2. Depending on when in March you are traveling daylight hours will start increasing.

3. A 1/2 day at Hampton Court is a great outing. Easy train ride out and back. Maybe that's the day you ride the Eye as sun sets and the lights of London start to glitter. Then walking over Westminster Bridge to Parliament square which is quite lovely at night.

4. Borough Market is nice but don't forget Brick Lane, Portobello Market or Camden Lock Market. You could walk along the canals if you went to Camden Lock.

5. Pretty certain the 7 year old would enjoy Mudchute Farm as well as all the water fowl in Hyde Park. Google about the feeding of the Pelicans. I'd also think your son would enjoy watching the Horse Guards.

6. A visit to Hamley's toy store should be on the itinerary.

7. A stroll across the Millenium bridge and/or if no one has vertigo, the Tower Bridge experience.

8. Before you leave checkout Timeout London website to see what's happening there during your dates. I get their weekly post for fun and always enjoy reading about events that are occurring. Things I'd never know about. A Timeout post advised me that September is the Thames Festival month with all sorts of activities occurring. Also referenced the different Thames cruise lines from Duck Tours on amphibious landing craft to afternoon tea cruises. Timeout is a font of information and a great travel tool.

9. www.walks.com Might be a walk you'd enjoy as a family.

10. Train to Salisbury, explore, then take the Stonehenge tour bus. Stay the night in Salisbury and train back to London in the morning.

11. Research to see where the unique Puppet Theatre Barge might be in March

12. Tower of London, Princess Diana's playground, National Maritime Museum and the Cutty Sark (parents rave about the Ahoy! Gallery for kids)

Guess you can see I'm suggesting spend more time in London.

Planning is part of the fun. Enjoy your trip.

I'm not sure how it would be during your time frame, but we really enjoyed Stourhead not too far from Salisbury.

https://www.nationaltrust.org.uk/stourhead

We've only rented out of LHR, but that was a couple of relatively easy roundabouts on the airport perimeter as a 'warm up' followed by congested but otherwise uneventful time in the slow lanes of limited access highways until the exit for Salisbury. Just watch some roundabout navigation and other UK traffic law explanation videos and have the person riding shotgun be watching the roundabouts for other traffic and calling out 'third left' and telling you which lane to correctly aim for while you concentrate on driving the car. And note that the road past Stoenhenge is prone to horrible traffic jams (too archaelogically sensitive to do what would otherwise be much needed road widening) so if your phone or sat nav system proposes a real time detour by back roads, use that direction set.

Legoland near Windsor Castle? Be sure it's open when you are there.

Claudia has lots of great ideas for London, and I'd suggest spending as much time there as possible. Take a train to Salisbury, see the cathedral, take the inner circle tour at Stonehenge, spend the night, and head back to London next morning for the rest of your trip.

Trains run half-hourly between Waterloo Station and Salisbury, the trip takes about 90 minutes. Easier than renting a car, fun for the kid, and you'll see some nice countryside. Use the link above to National Rail to plan this. I don't know how the inner circle tour works, whether it picks you up in Salisbury or requires you to get there on your own, but if necessary there are hourly buses from Salisbury to Stonehenge during the day, again see the link above. You should be able to arrange a taxi to take you back to town after the tour if you need to.

Then train back to London for more fun along the lines Claudia suggested, or whatever else interests you, and an easy connection to Gatwick for your return flight. With just a week, I wouldn't try to do too much, especially with a young child. Bath and Glastonbury are "a bridge too far" for this trip, I think.

You have already received many good suggestions. Claudia's list is great.

During our last trip to England, we stayed a week in London, then headed out by train. We left Waterloo Station, arrived in Salisbury. We stayed in a hotel, walking distance to shops and the cathedral. Salisbury Cathedral was one of the reasons for our trip there. It was magnificent. They have their own copy of the Magna Carta on display there. The second day we were there, we took the Stonehenge bus out of the town center. Lovely ride through countryside out to the stones. Takes you to Stonehenge and Old Sarum, brings you back to town center. No need for a car or taxi. You can buy bus ticket at the Tourist Information Centre in downtown Salisbury, on Fish Row, just off the Market Place. Make sure they know you only want bus tickets, that you do not want entrance to Stonehenge included. Or you can just buy your bus ticket from the bus driver when you get on the bus. Make sure he also knows you do not need it to include entrance to Stonehenge, because you already have that.

Then we took the train to Stratford-Upon-Avon, passing through Oxford. The first day in Stratford-Upon-Avon, we walked around to the Shakespeare houses, the church where he is buried, and went to the Royal Shakespeare Theatre. Lots of good restaurants, coffee shops and shops around town. The second day, we took a tour of the Cotswolds with the company "Go Cotswolds". Small van. You're not with a huge crowd.
https://www.gocotswolds.co.uk/
The tour started early in the morning and we returned that afternoon. The Cotswold villages were lovely. I highly recommend this company. See my review here:https://community.ricksteves.com/travel-forum/day-tours/go-cotswolds-tour-with-tom-the-most-fun-we-had-while-in-england
Your son would enjoy the Cotswolds tour. You see many sheep and lambs at the Broadway Tower stop. Plus, in the cutest village, Bourton-On-The-Water, there is a toy shop and an ice cream shop. There is also a stream (technically the River Windrush) running through the center of town with stone bridges over it. Lots of cute ducks and swans on this stream. The kids seemed to love it.

Very near Stratford-Upon-Avon is Warwick Castle, which your son would enjoy. I think the adults would enjoy it too. It is a real medieval castle, with jousting and falconry displays on some days. Check their website for which days you can see these things.
https://en.wikipedia.org/wiki/Warwick_Castle
https://www.warwick-castle.com/

Easy train return to London. Put us into Marylebone Station.

I would suggest Stratford-Upon-Avon and Warwick Castle for your next stop after Salisbury/Stonehenge. I think you would really enjoy these places and the Cotswold tour. Trains whisk you quickly from one place to another, so you don't have to worry about long travel times. I would not consider renting a car because you don't need it. That would only make your traveling more difficult, in my opinion.

From Marylebone Station, you could take a taxi to Victoria Station and take the train (Gatwick Express) from there to Gatwick Airport. Or check into a hotel near Victoria Station, then train out by Gatwick Express the morning of your flight.

Thank you so much to everyone who replied; you gave me such great suggestions and information! Sorry I didn't reply back sooner; some things at work were consuming nearly all of my time over the past week, and I am just now catching up on the rest of life.

I think we're going to look at just doing one night in Salisbury, then heading back to London for the remainder of our trip. I can't thank all of you enough for your responses.

Bath is great. Have you considered Harry Potter movie set? My 7-yo and 10-yo are dying to go!

What does your son enjoy or is interested in? My 8 year old loved trains, buses. So we made sure to ride a double decker and the underground multiple times. The transit museum was great as well. The Princess Diana playground was terrific. He was underwhelmed at hemleys toy store.
We ended up staying almost the entire day at the Tower of London as they had some amazing activities and demonstrations planned and so we ( I ) deviated from whatever we had planned for later in day and stayed. The London Eye was terrific.
We also went to York - great train museum, walled city and a Viking exhibit.
Harry Potter - was not built but he went on a different later trip and loved it.
We also saw a show one night - it was terrific. not sure whats there now but im sure there is at least one child friendly show.
(I am getting nostalgic for that age and that trip. My son told me on the way home that his favorite day was the last day in London'when you finally relaxed and just let us ride the underground to all the stops" Guilty as charged, but i did find that letting Nick make at least one of the choices of 'what to do' each day made for a great trip- maybe different than an adult one but still great. So we spent more time inparks than i would have but I got to meet some lovely mums and share notes on our different educational system.) Enjoy

Each of you should take a warm scarf and gloves/mittens and maybe a hat or hood on jacket.

You might consider Avebury https://www.nationaltrust.org.uk/avebury and Lacock Abbey and Village https://www.nationaltrust.org.uk/lacock-abbey-fox-talbot-museum-and-village, both north of Salisbury. Read about them and see pictures at the included links.
If you go to Lacock, be sure to have hot-from-the-oven scones at "Sign of the Angel."

London zoo! Our college daughter wanted to go there in Dec 2014. We would never have gone there but we loved it-with England's worldwide empire, it has some fish and snakes we don't see in American zoos.

Fri: Arrive late and stay at Gatwick (1 night)
Sat: Train to Salisbury (3 nights)
Sun: Stonehenge Tour
Mon: Day by train to Bath (approx 1 hour each way)
Tue: Train to London (4 nights)
Wed.Thu.Fri: London
Sat: Depart Gatwick

Consider the other sites like Stonehenge. Avebury Circle, Old Sarum, and for me Silbury Hill with the West Kennet Long Barrow were great. Wells and Glastonbury were wonderful. And Bath, even for just the Roman Baths, is wonderful. I loved seeing the studios where Harry Potter was filmed. If your son is at all interested, go! Get tickets as soon as they are available. In London there are some London Walks that I'm sure all of you would like and the Tower of London is a must. Have fun!

Please recheck your Stonehenge time - believe it is 6:45AM instead of PM. I am finding that 6:45 PM is usually shown as 18:45 when booking in UK. We are taking a similar Inner Circle tour in March and ours is 6:45AM. Hope this helps.

Thanks, I rechecked and our time is 18:45 / 6:45 PM. When we originally booked over the summer the time was listed as 16:45, but English Heritage emailed me in September to inform me that the time was rescheduled to 18:45. They have not further changed the time.

We just did 28 days in England and Wales, driving on the left. We avoided London and the SW England, since we had done that four years ago.

Driving on the left is easy when on major roads, but adjusting to the roundabouts and turning is a constant concern. Thanks to my wife for constantly reminding we to stay on the left (especially when making a right turn).

Rent an automatic and be sure to have a GPS or NAV system. Some car rental offices charge way too much for either. You can buy a GPS with UK maps for less than the rental agencies.

When driving in the South of England plan on it taking a lot more time than it would in the USA, Traffic is heavy, particulary around London (avoid the M25 if you can).

Parking is a concern with a rental car. You will need to keep some pound coins for that as well as smaller coins for the toilet.

Bath is wonderful, as are Glastonbury and Wells, but Bath is a full day to see and Glastonbury and Wells at least half a day.

Here is my cruise critic review of our drive tour.
https://www.cruisecritic.com/memberreviews/memberreview.cfm?EntryID=599139

If you do decide to rent a car, try not to rent from an airport site - the extra cost is not worth it if you can pick one up elsewhere. If you do rent & pay with a major credit card, you may not need to include the extra insurance charges. Check the benefits on your card.

It's been a while but I do recall enjoying wandering around the ruins of Glastonbury Abbey, possible burial site for King Arthur.