Finding a Sangha in London

I've been what you might call an armchair Buddhist for many years. I'm at a point where I'd really love to meet other like minded people and get involved with the Buddhist community on a more personal level. I live in London. Having listened extensively online to Dharma talks from wonderful teachers like Gil Frondsal, I can see there are a great many communities in the United States which spread the Dharma. I was wondering if anyone can point me in the direction of similar communities in the UK, specifically London?