Hi @tracy1982, the great thing about London is there are lots of buses you can just sit on, which go past interesting places, you don’t have to walk it all. Also I’d recommend the boat – you don’t need a fancy tour, you can just get on a commuter boat. We wanted to do some sight seeing with my nephews without doing too much walking and got the Thames Clipper from the London Eye to the Tower of London. They absolutely loved it, you could see lots of sights from the water and the boat was part of the adventure too. https://www.thamesclippers.com/plan-your-journey/route-map
Hope you have a great time!