I think that the Sainsbury's car park is actually the Council's now. I know that Brockley Market is in a car park but it is at least visible from the road. This strikes me as a good feature for a successful market - to site it behind Sainsbury's seems a little hidden away to me.

Isn't there a bit of space in front of Sylvan Post? Also, there is a wide pavement down from the station at Honor Oak Park that I think would be suitable for a small market.