As we're all computer enthusiasts, how about Bletchley Park... while you can, since it's been in the news that it's in a pretty poor state (I'm going there this weekend, as it happens). I did a brief visit there with school last year, and it is interesting seeing the reproduction of Colossus (arguably the world's first computer, used to break the Enigma code) as well as the other old kit like a 1KB RAM module which is about the size of a modern PC case!
