There is a market this Sunday (10am-2pm) and we hope to continue this once a month at the station forecourt.
We deliberately chose Sunday as Forest Hill is particularly quiet on a Sunday and to avoid clashing with the weekly Saturday Brockley market (the Catford market were less considerate when they decided to use the same Sunday every month as Forest Hill, but it doesn't really matter).
We have some ideas about extending the market beyond food in the future as you have suggested, and have identified ways this could be done. But I'm a strong believer in taking small steps and building something that will last longer.
If there is considered to be enough demand for a weekly market then we could try it out, but the licensing is very different (you actually need planning permission). what we really want is for the demand at the market to lead to new shops opening along the high street, so that we have better shopping opportunities every day, not just once a week or once a month. This is demonstrated by the opening next week of a deli in Dartmouth Road by one of the market stalls.