Arduino-ites in London (that means you too mem!)

Yes, definitely worth finding out about Bletchley Park: http://www.bletchleypark.org.uk/

Or if you want a trip further afield, there's the (sadly grounded) Concorde at Filton: http://www.concordeatfilton.org.uk/
That one, of course, is near Bristol, and not far from where I live (nearest station is Bristol Parkway).