Hi Marco,
I would have thought Richmond Park would be a good place to go to recruit new members.
I was there a couple of weeks ago and you get loads of cyclists , even a few girls !!
I reckon you need some kind of ACC banner and a sign offering coffee/tea and and hand out club info sheets and application forms.
This would probably work at the cafe at the top of Box Hill too .
If its ladies you specifically want to target than I'd try to get a couple of the lady ACCers to go with you or you risk seeming a bit creepy.
Probably best to try it in the warmer weather