I went to a meetup before with some Warriors were there, Andy Henry, Martin Avis, some other people. This was years ago.
People tell you what they're doing, but they never share their big secrets. You do find out a few nuggets though and you should share a few of your own too.
It's definitely worth doing and I bet a BHW night is WAY better! I suggest a monthyl meetup, find a drinking hole that will always have space.
I might suggest the bar near Baker Street tube, the huge one where you walk up the stairs? It's nothing special but due to sheer size there is no problem meeting up, small party or large, plus Baker St is good for transport links.