Indoor arrival day activities with kids?

The London Transportation Museum at Covent Garden should keep them occupied for at least 2 hours.

I agree with the recommendation of the London Transportation Museum. It is located in/near the Covent Garden Market. Most (if not all) of the market is covered , so wandering the stalls can be a fun dreary day activity, too. And there are usually so decent to excellent buskers (performers) around that area, too (could be anything from jugglers to classical music groups! ).

If it rains, the Natural History Museum is a great place for kids. Here is the link to the site with visitor information: https://www.nhm.ac.uk/. While it can get quite crowded, it is free to enter and you can spend as little or as much time as you would like.

Another option is the Science Museum, not far from the Natural History Museum. Also free, it offers an interactive wonder lab (need to reserve). Here is the link: https://www.sciencemuseum.org.uk/.

Hopefully you will get good weather as being outdoors is the best way to combat jet lag.

Have a great trip, London is a blast for kids (and adults).

Sandy

Just remember it’s the weekend so the museums will be crowded.

Once you’ve checked in to your accommodation Visit
The Grant Museum Of Zoology. https://www.ucl.ac.uk/culture/grant-museum-zoology

Rain in London is part of the experience. Don’t let it deter you from enjoying your visit.

I don't understand what is wrong with your original plan! Walking in the rain can be quite pleasurable if you have the right gear.

We arrive Sat morning too! (From DC) Have a safe flight and great trip. The weather forecast seemed to change again and now Sat looks like the ONLY day of rain (I get this could change) but so happy. It seems so much cooler there but still beautiful.

Keep your kids outside as much as possible. They won't melt. Moreover, weather constantly changes so it might rain for a short bit and then stop. That's what umbrellas and raincoats are for. Kids AND adults won't appreciate any indoor activity on the day they arrive as they'll just get more and more tired without constant fresh air.

Thanks for the feedback everyone. We all have rain jackets with hoods so I was really just thinking for a backup plan if it happens to be pouring rain. We can handle a light on/off rain. :)

I also realized that I need to pick up our London Passes near Trafalgar Square, so it probably makes sense to do this on Sat instead of waiting until Sun when we want to start using them as the desk doesn't open until 10:00. So we can go to Covent Garden, walk along the river, or even go over to Hyde Park to the Princess Diana Playground if the weather cooperates.

@laurenarky24, I hope you have a great trip too!

There is a fantastic climbing gym in a castle out just northeast of the city center...it's about a 15 minute tube ride from King's Cross...here's the link if you want to check it out! My son climbed there was he was at university in London and it's pretty unique...your kids would probably love it! Might be a nice way to spend a few hours...they have an onsite cafe as well. Pretty cool place!
The Castle Climbing Gym