There are plenty of photography galleries on display at the Victoria and Albert Museum. Some of them are ticketed while others are completely free. There is one that you should check out if you are a fan of photography and of improving your craft and that is The History of Photography. The museum has a collection of over five hundred thousand photographs. Seeing the photographs of famous and hitherto unknown people and how it has evolved over the years is a fascinating feeling.
So next time you are in London, go spend the day. It won't take long if you stay in the city at hotels like Berjaya Eden Park London Hotel for example. It is a lovely and informative way to spend one's day.