Hee, London Aquarium... looks good! : )
This is somewhere the cubs particularly want to visit - Legoland UK.
Colchester Castle is a place close to my heart, love to go there again and Land's End intrigues me. So does this place - I've wanted to see the Uffington Horse ever since I found a picture of it when I was about 9.
And of course there's all those wonderful places in and around Bristol... *g* How long can we stay, Joules?

I'm thinking of getting a nice, big map of the UK so the cubs and I can make a thumbtack wish-list of the places we'd like to visit. : )