I have a weekend in london in the end of november and I'm wondering what museums should I prioritise. I've been in london before and seen the famous buildings.
Depends what interests you... British Museum, Science Museum, Natural History Museum, etc.
The British Museum should be a given - you could easily spend two days there alone. Otherwise, the Victoria & Albert Museum has a really nice medieval gallery. I've not been to the Imperial War Museum since its recent refurb but I'm sure there's plenty of WWI events on.
In terms of art, and this is obviously completely random, the National Gallery also has a good collection of medieval works while the Tate Modern has a room on Soviet propaganda. The British Library has got an exhibition running on the evolution of the Gothic tradition, which I'm planning to see at some point.