Just wear what you're comfortable in so that you don't overheat, it will take some experimentation. I know people who run in t-shirt and shorts when its 0 outside, so just down to taste. If doing a hard session where you will heat up very quickly I would stay with a t-shirt, gloves and half tights in those conditions. If steady/easy running or a long run then gloves, tights, and a long sleeve top or a t shirt with a wind jacket on top.
Anyone done this or any other of the Rat Race series? How extreme is it - on a par with Tough Guy or less risk of hypothermia and more about the running? is the course incredibly muddy or average trail/xc fare (so do I need trail shoes...)
I can't believe you can't seem to find a similar club; having lived in greater London and studied in the north east have to say that south-west London has one of the biggest choice of running clubs. The atmosphere that you are looking for, convenient training times etc will dictate which suits you best. Google these:
- Clapham Chasers (as stated above, based in Battersea Park)
- Wimbledon Windmilers
- Hercules Wimbledon AC (more track based than the above methinks)