Upvote:1
Try www.samatha.org with some experienced local groups.
Upvote:1
Perhaps not in London but not too far away are two monasteries well worth the trip. Amaravati (http://www.amaravati.org/) Cittaviveka (http://www.cittaviveka.org/)
There is also London Buddhist Vihara (www.londonbuddhistvihara.org/) closer to home.
Upvote:2
I've been to London Buddhist Centre and that was very good. It's part of the Triratna Buddhist Community and it's explicit aim is to present the Buddha's teaching in a way that is compatible with modern society. It's in a converted fire station so it's a really good space and it was friendly when I went.
I am biased though - I'm involved with Triratna in Leeds so it's my sangha. I think it's still a good recommendation though.