Rare non-PL post, but I figure this one is worth it.
I went to Bletchley Park last weekend, and had an absolutely fantastic time. There was a lot more there than I expected. It's an absolute bargain at £10, and it's only about 45 minutes on the train from Euston station in London. It's definitely worth doing one of the free tours, too. The guides are extremely knowledgeable and entertaining.
Also located there is the National Museum of Computing, which was fascinating. I took some pictures:
And one of me standing in front of a PDP-11 looking quizzical:
So, if you are in the UK, or are planning a visit, definitely make the effort to get to Bletchley Park.