England counrty side

Smaller places generally do not have stations, and even if they do they do not have enough to fill a whole day. Castles and stately homes are in the countryside and require a car to reach.

There are lots of medium sized and large towns you can reach by train from London. The list is enormous, but to begin:

• Canterbury (cathedral, old town and city walls).
• Lewes (old town)
• Rye (smaller old town)
• Winchester (cathedral, old town)
• Salisbury (cathedral, old town)
• Oxford (University and town)
• Cambridge (University and town)
• Windsor (castle). Just outside London.
• Plus places technically in London but further from the centre
  • Hampton Court Palace
  • Greenwich (reachable by train or boat).

I like York, but that is further away (2 hours by High Speed Train) and deserves 2-3 days.
I am sure others will add their favourites.

If you feel very adventurous, you could travel by train to Stratford upon Avon. Although very commercial, you are then close to cool places like Warwick castle (love that place) and Tanworth in Arden. Growing up place and final resting place of Nick Drake, and The Annual Nick Drake Gathering. If there is a vacancy at The Bell Inn (9 room inn in the heart of the village) definitely worth spending the night. However, the 2 train stops that srvc Tanworth, Woodend and Danzey are about a mile out of the village. You could call for a cab if you don't want to walk.
https://thebellattanworthinarden.co.uk/
https://www.warwick-castle.com/
https://www.youtube.com/watch?v=yqtN1HWG_0s
https://www.youtube.com/watch?v=jEglPLHtKWQ

Depending how much you want to walk I would recommend taking the train from London Paddington to Either Newbury or Kintbury and walk along the canal to Hungerford. The trains run every hour to Bedwyn and you can time it right to catch the train back. Check out the link http://www.gps-routes.co.uk/routes/home.nsf/RoutesLinksWalks/newbury-to-kintbury-and-hungerford-canal-walk-walking-route

This is a good question and well timed for me. I'm looking into this right now. We will be in London the last week of September. Also without a car. I am thinking about a day trip to York and possibly a day trip to Edale in the peak district to walk a short portion of the Pennine Way. I'm open to other suggestions. Partially because the Pennine will require us to declare that we came into contact with livestock/livestock fields. It shouldn't be a big deal. They'll just wash our shoes, but I'm not sure if my fiance might get annoyed with that.

On our last trip we took the train to Eastbourne and walked a short portion of the South Downs Way along the cliffs at Beachy Head. That was an excellent trip but it was cut short because I started coming down with a cold. Part of me wants to repeat that trip so that we can finish it the way I had planned it, but then again I also want to go somewhere new.

I'm also considering Skipton on the outskirts of the Yorkshire Dales to see Skipton Castle, but I'm not sure if there are any walking trails around there that we could explore after seeing the castle. I think there is one near the castle but it's in woods and I'm not too keen on woods. We have plenty of woods here in North Carolina, USA.

If you like museums and cathedrals, I highly recommend Salisbury, York and Durham(university town feels smaller than York but it may be too far for a day trip from London-its lovely at night with a walking path along the river). Both are easy to get to and get around in without a car.

You might also consider this guided day tour of the Cotswolds by minibus, Becky's Secret Cottage Tour.
https://www.cotswoldtourismtours.co.uk/

I did it last June - very enjoyable day.
They meet you at the Moreton-in-Marsh rail station (an easy train trip from London).

On the way back to London, I stopped off in Oxford for a few hours (my "anytime" train ticket allowed me to break my journey), and although most sights were closed by the time I arrived around 5p, I did enjoy walking around and seeing the buildings from the outside just to get a feel of the place.

I hope you enjoy whatever you choose!

If you take the train to Oxford you can also take a bus to Blenheim Palace and the town of Woodstock. Oxford has the famous Ashmolean Museum and the Oxford University Museum of Natural History. This might be a very full day but the trains run fairly often so you don't have to time things so tight. York seems a long way to me for a return day trip, but the York Minster may be worth the trip. Look at the National Trust Web site for some ideas.

You could take the train to Moreton in Marsh (1 1/2 hr ride), once there you can take a bus or taxi to Chipping Campden, Stow on the Wold, Broadway or Bourton on the Water. There are trains leaving Paddington Station at 7:50 arriving 9:25, 8:21 arriving at 9:59am., there are earlier trains. You would have time to visit at least two villages. There are trains leaving for London every hour, so you could stay as long as you want.