I tried the Cambridge SPA group. Only managed to get to one meeting. There was a good talk on Software Decay, and an cringe-inducing moment as one of the participants suggested that older people couldn't program, only to find himself in the same room as Tony Hoare. The rest of the programme unfortunately doesn't sound as interesting.
There's also Software East, but that seems to have more of a process theme, rather than in-depth technical gubbins. Not sure what else there is in the East of England.
Today, Joel on Software announced that there would be a Stack Overflow event in London in October. Sounds exactly what I'm after, so I've signed straight up!
The conference is for programmers. The conversation is going to be hard core. Speakers are going to be writing code.