I'm currently in London for a large Week-End. In this city, churches do business, even when under heavy work :
Yesterday I visited the Photographer's Gallery where you can currently see (among other ones) great pictures by Philippe Chancel taken in North Korea. I enjoyed a small breakfast in their cafeteria (nice lemoncake). Then I went to the National Portrait Gallery where I especially enjoyed recent works.
I had a Fish and Chips in the first pub I met but was disappointed by the beers they offered (Foster, Stella, Kronenbourg) and then walked to the Tate Modern which is very large. They have a lot of different galleries, so I'm sure you will find some that you enjoy. I was impressed by the amount of famous surrealist works. I then had a cup of tea in the Bramah Museum where they bring it with a sand-catcher so that you drink it at the perfect time.