I have tried to see this museum a few times, but the queues have always been ridiculous. However, today I was in good time for a meeting at Westminster and as there was no queue, I took the opportunity for a look around.
In essence, this is the WW2 bunker that Churchill and the war cabinet moved into when the bombs started dropping on London. You see the cabinet room, meeting rooms and the operational rooms.
The map room is particularly good. With statistical reports etc.
Pins and cotton in WW2! In fact, I recall running an early wargame campaign using similar materials pinched from my Mum's sewing box. The atmosphere must have been horrendous as folk were obviously allowed to smoke. Mind you, I suppose no one was going to stop Churchill.
And of course, Churchill's bedroom where he famously dictated letters etc. And smoked!
There is also a Churchill museum, which has some interesting exhibits covering the highs and lows of his controversial career. Not to mention his childhood wargame collection!
I should warn that this is not a cheap admission (£22 for an adult), but some other IWM sites are free so I suppose it balances out. It is worth a look.