The club I sometimes ride with,
Bigfoot CC, has seven levels of ride, ranging from 1 (super fast guys and gals with racing licenses and stuff like that) to 7 (gentle pootles for beginners) and is very welcoming. If you are riding off the front or generally going too fast, (or don't seem miserable enough on the hills
) then it's politely suggested that you move up a level. If you are struggling with the pace - or hills - then (in my experience) the ride waits for you at regrouping stops. All extremely friendly, welcoming, and civilised, and I'd recommend them wholeheartedly whatever your level if you happen to live near Bromley.
The only reason I don't ride with them more often is that their group rides are a bit short for my taste (about 50-60 km) - if I have a free day then I like to do 80-150km quite slowly, but I do go out with them when I only have a half day free on a Saturday. That and the fact that I'm a grumpy sod who likes riding alone.