Thanks, gbs. I'm aware of those. Both will indeed be great pootles for those wanting to explore, admire & learn about their surroundings and socialise.
What I'm looking for in particular is a regular Sunday ride-out with people faster than me (not hard to find, surely?!), which will challenge me and 'force' me to improve, especially my speed (both average and top) and technique on hills - though not both issues together, at least not for a few months!
At the moment, I am not quite able to keep up with Addiscombe CC's '15' group. They do run rides slower than a 15mph average but only once a month. Likewise I believe with Dulwich Paragon, though I haven't been out with them (yet) because frankly Crystal Palace as a starting point is a turn-off for me... I mean, starting the day by going straight UP?! No thanks!