Bus tour is absolutely part of the plan, DD is excited about going on the top deck of a double decker, hopefully it will be open top. She is nearly 7 so doesn't need play areas etc. she will want to do "grown up" stuff - it is just DD and me going so she excited about having me "to herself" in itself, and wants us to do things together :) The science museum is definitely a possibility. I don't want to try and fit too much into one day, and I also don't want things to be in any way stressful, rushing about etc. We will go to Leicester square and buy tickets to a show though, that is another thing we want to do - we'll have 3 full days even though only 2 nights, as our flight there is early morning and flight back is evening.
Actually that reminds me, we are flying into Gatwick, which is the only London airport I haven't used often (used to fly out of Stansted 2 or 3 of times a month at one point while I lived in London) so I'd better check how to get from there to central London!
Nuttella I booked it when DH and 2 of his mates decided to go to Edinburgh for some convoluted reason, but basically on a jolly, on May. I just thought why not? Trips to the UK end up so much about the "duty" of visiting my parents, and it is so expensive because my parents live in the back of beyond in Yorkshire, 2 hours drive from the nearest airport - and flights to Manchester are at least 50% again more expensive than to London... but getting just myself and 1 child to London is actually vastly more affordable than getting a family of 5 to my parents, and a family room in a central London Youth hostel is only ?60 per room per night even at this time of year, so I went for it :) We are flying out of Stuttgart as it turned out quite a lot cheaper than Munich for some reason!