I'm a bit late to this thread, but even though I'm an avowed Note-Orian, and therefore a little biased, I know you would find loads of fun and a brilliant sense of community at any of Note-Orious, Goose Green or Nunhead choirs (and the others mentioned here that I'm not familiar with). Definitely try a free taster session with each of them, I'm sure you'll get a sense of the best fit quite quickly. But in general I can't recommend enough being part of a local choir for feeling connected to the area where you live and finding friendship and support around you. As well as all the fun music stuff. Hope to see you soon!