If you go to the Events tab (top second right) and enter your criteria into the search box, you should able to find a fair view London races this Autumn.
I'd recommend the Richmond Autumn Riverside 10K, I did the spring one as my first ever 10K and am going to do the autumn one as well. Run from Ham House entirely along the riverside towpath, very pretty and good atmosphere.
Comments
There's a 10k in Battersea Park on 1st October (Saturday) at 8am..run by these guys:
http://uk.srichinmoyraces.org/races/london
I think its about £10 and is a 4 lapper of the flatest park you can imagine! Great if you want a fast time.