Hello Claus. I can highly recommend the Royal Signals Museum at Blandford in Dorset
www.army.mod.uk/signals/museum (it's inside the army camp so you need ID)..in the same area is Bovington tank Museum
www.tankmuseum.org/home and if you need some lighthearted/family entertainment try Monkey World just accross the road
www.monkeyworld.co.uk Have a wonderful time in the UK.