Expect long lines. It was very popular and they only let a few in at a time. The actual rooms where Churchill talked to Roosevelt ona secret phone line, the conference room where many top-level British and Allied discussions took place, and even the private quarters where Churchill used to sleep are a powerful draw for the British people. It's also a great immersion into World War II History in the capital. Right-click and choose "view image" to enlarge.
Welcome to the Imperial War Museum The Imperial War Museum, the multi-branch national museum of war and wartime life from the First World War, through the Second World War, to the present day.