Imperial War Museum:

Well worth a look, in central London. It is the original "Bedlam" psychiatric hospital which gave it's name to the commonly used description for a chaotic situation, however, unless you are told of it's origins it appears to be just another industrial building. What is on display is a real "potpurri" covering all facets of the war. For detailed displays of a particular subject you need to go to the relevant museum eg., Bovington for tanks, Duxford for planes.

There are lots of specific military museums in England. I am interested to know where they have the midget X class submarines of Tirpitz fame and "Chariot" human torpedo. Pic shows German Jagdpanther in distance, Russian T34 closer, English Daimler? armoured car.