Not sure how much time I need on London and confused about transportation

Answer might depend upon how long you plan to spend at each sight. Some things, like riding the Eye, take a set amount of time, once you’re onboard. Things like The Tower or museums can take a whirlwind 30 or 40 minutes if you just whiz through and say you were there, or can take hours and hours if you linger or view everything there is of interest. At Buckingham Palace, are you planning on swinging by to have a look at the parade ground and the front of the building, or waiting to see the Changing of the Guard? We’ve found it generally works best to have one, or at most, two big, time-consuming destinations in a day.

The Underground (subway, or “Tube”) has generally been our preferred means of transportation around London, unless walking to sights is practical. Every once in a while, we’ve taken a taxi. Haven’t used a public bus there, yet.

Not sure when you're going, but check that all those things are open when you're there. Buckingham Palace is currently closed to tours until July 20th. https://www.royal.uk/summer-opening-buckingham-palace

Big Ben is also currently covered in scaffolding but you can see the clock face.

Recommend the Hop Off/Hop On Bus for your first day to get a view
of many of the major sights and included usually is a free boat cruise
leaving near Big Ben. I think it is on a 24 hr basis so you could start out
an hour after it opens your first day and still have a ride somewhere you
want to visit the next morning.

Dont underestimate the time it takes to wait in lines, including security lines even if you already have tickets. We had tickets for the Eye, for example, but it still took us two hours in line to board. Also getting from one of those places to the other takes time. So prioritize.

The Duck Tour had a significant safety issue while in the water a couple of years ago and they were forced to suspend operations.

I don't know what has happened to them since, but like emma I can't remember seeing any of the bright yellow vehicles for the last couple of years.

Darn, you are right, they are not doing the water tours, I guess that is off the list.

Please note that we are no longer able to operate our usual range of tours due to Thames Water’s compulsory purchase of our slipway to build the next phase of the Thames Tunnel super sewer.

I will be there after July 20, so I should at least be OK there but also a bummer on Big Ben, any idea if they will be done by August?

As for my confusion about the transportation I will be flying into Gatwick, I know I can take the train in. I also see I can buy train tickets online before hand but I also read that getting a visitor oyster card might work?

Basically I am trying to figure out what to buy ahead of time, I would rather have as much planned/purchased before hand so I am not trying to figure things out on the fly. It sounds like I can buy a visitors Oyster card for myself which would cover the train but my kids don't get an oyster they get the travel card but that doesn't cover the train. So I'm not sure what to do there.

Also when I get off the train in London I have to take the bus for a short while to get to the hotel, do I just use the same visitor oyster card?

This post seems to answer my question about the cards, I have an 11 and 14 so I think I just will just wait and get the cards at the airport for them to get the young person discount?

Purchase Oyster Card at Gatwick Airport? Not Visitor Oyster Cards

You did notice to get a real Oyster card, not the expensive (no refund) Visitor one?

Big Ben, the Elizabeth Tower which is its real name, covered for 3 years is my memory.

Yup, just checked - 2021. Scaffolding and the bells are silent.

All the official information is here

No guarantees that all will finish on time... or on budget

Bummer on the scaffolding but nothing I can do about that. We will be staying in Clapham, I was going to buy tickets here but seems the Oyster card will cover it?

https://ticket.thameslinkrailway.com/search

Why is the British Museum not on the list? If you like museums at all, it is essential. And after what happened in the US, I wouldn't even consider taking a Duck tour.

It is right by the Clapham Common (park?) according to Google maps I would take the London Victoria train to Clapham Junction, then walk to the 87 bus and take that a few stops to our hotel. Should a Oyster card with 25 pounds be enough for this trip plus the other stuff I listed?

I'm not super big into museums however seeing the rosetta stone would be cool in the British Museum.

It doesn't cost any more to be in the British Museum for 4 hours than 10 minutes - completely free (except special temporary exhibits). Donations accepted.

The Rosetta Stone is popular - best to be patient or go when the crowds are less.

Sounds like you are flying from SFO or LAX. I fly the out of LAX nearly every year to London Heathrow.

You say you are arriving at 2pm. Understand that it can take hours ( even at Gatwick) to get through immigration. Then time from Gatwick to your Clapham Hotel. Can only surmise you chose the Clapham neighborhood because of a cheaper accommodation rate. Staying there means more transport time to and from the sites.

Thus you need to mentally prepare yourself that you first “day” in London will be a bit more frenzied. I say this because it’s possible you will be using public transport during commuter times. Just remember if a train is too jammed merely wait for the next one.

Use this helpful website to plan your public transport.
www.tfl.gov.uk

So once you do check in familiarize yourself where the closest bank ATM is located ( believe there’s a Barclays Bank fairly close) and withdraw your pounds. Also look for the market where you will get your snacks and bottled water and closest coffee shop.

If everyone is “ starving “ then eat. Look for a spot near your hotel.

If everyone is still raring to go use your Oyster Cards at Clapham Common Underground and take the Northern Line (Black) to Stockwell. Exit and then take the Victoria Line ( Light Blue ) to Victoria Station. Exit Victoria station and to help adjust to jet lag walk the few blocks to Buckingham Palace. Photo ops and then follow Birdcage Walk into St James Park towards the clock tower that’s in scaffolding ( Big Ben ) and Arrive in Parliament Square. More photo ops then walk across Westminster Bridge and watch the lights of Parliament turn on. From the bridge walk over to the London Eye.

More photo ops and time to head back to get some sleep.

Next day be at Tower Of London when it opens and go straight to the Crown Jewels, then see the rest of the Tower. Then photo ops for Tower Bridge.
Add walking from there up to Leadenhall Market for lunch. Then make your way to the British Museum.

One last suggestion. Get the Rick Steve’s Guidebook.
Will answer the majority of your questions, as it is chock full of helpful insight regarding London.

You would definitely need to add a third day if you add more. Maybe group items that are near each other each other into each day. From the river bank /London Eye, you can see the one side of Big Ben where the clock is not covered with scaffolding. Substitute a boat cruise on the river for your Duck Tour.

Churchill War Rooms, Westminster Abbey, Buckingham Palace , London Eye are all walking distance apart.

Unless you are there during the time when Buckingham Palace does tours-maybe August?-you should go to Windsor instead-it's an easy day trip from London on the train.

We are Flying into Gatwick and I am planning on staying at the Clapham Premier Inn. We will be there end of July/early August.

@Emma nice to know you read my posts.

I’ve learned something new about the Clapham Common area now because of your first hand knowledge.

As the exact locale of the OP’s accommodation has been shared I eagerly await your post about best public transport option.

That location is a bit no-mans land for trains and tubes. It'll be a bus to train job, I expect.

Would you all suggest a different Premier Inn? The reason I picked this one is because it was in the middle of the things we wanted to see but at a good rate. I could move closer into the city but I expect I will pay more.

For two full days, your current plan is not an issue, given some of the earlier input. I hesitate to change peoples plans, but I think you could use some help, to really get a sense of London. Here are my thoughts so far:

Big Ben As others mentioned, covered in scaffolding, but even then, no more than a walk-by

Natural History Museum Everybody likes certain types of museums, but in a half dozen trips to London, totaling close to 2 months of time, I do not think I have been here. I just think that there are more iconic museums. As someone mentioned, if anyone has only one museum to go to in London, it should be the British Museum

Buckingham Palace As was mentioned, due to closure, no tour, so like Big Ben, a wander up and see it, maybe catch a changing of the guard

Tower of London Well worth it, figure most of a morning or afternoon

Tower Bridge For the most part, a walk around and look at it, easy to do with the Tower of London

London Eye A couple hours if you have to wait, can be combined with a South Bank walk

Duck boat tour As others mentioned, no longer around, there are other Thames cruises, worth looking into

Aside from your plans so far, what does interest you? I suggest getting the Rick Steves London book, there are several "Walks" you could do (Like Big Ben, Parliament, up Whitehall, etc.) and it may point out some things that interest you. Some of the notables would be Churches (Westminster, St Pauls, Temple), a Few more Museums, WW2 related sites, Markets, and more.

We've been planning our trip for about a year now and seems every time we open our computers or talk to someone we find something we haven't thought about... but we are going this summer and are pretty much stuck to the plan.

We started with Rick Steves 3 week plan making London the last of our trip for a total of 5 days. We are staying at the Rubens which is right in the middle of it all (we think). We really wanted to end the trip on a good note. While it appears a few things will be closed our goal is to relax and enjoy London - no time pressure. And if we do get bored (which I doubt) we would like to see Dover and could take a train out there and back.

The other thing too we've noticed it really all depends on your personal preferences, what you like to do. For the most part we like to hike and be outdoors, urban hiking, too, and take photos. We hate lines but they can be fun to watch...