Getting started with long distance rides...

I'd appreciate some tips from people on how to get started sensibly, without overdoing it.
Do people here do long rides alone or in a group?
Maybe someone has started long distance riding lately, and could tell me how exactly that went along?
Also if anyone knows clubs and organized rides in and around SE15 area that I'd definitely should look at, that'd be greatly appreciated.

I generally ride alone. Here in Swindon I find it difficult to find people who are interested in heading out on nice long rides that aren't done at road club pace and don't take time to sample the delights if good little cafe stops and pubs along the way. It's something that I miss from when I was a filthy leper Londoner. Luckily I'm quite happy with my own company.

When I was degenerate scum a Londoner I generally hung out with Southwark Cyclists who run a range of quite casual and informal rides of varying lengths. Best thing to do is turn up to one of the afterworker rides on a Thursday and have a chat with Barry Mason about what rides are coming up.

Other than that, the forum rides should be good and some of the other LCC borough groups will run good rides of a similar format.