the p4 to brixton is the route I use as it involves no steps ( which is great when you have a suitcase full of christmas presents!) but you need to check the victoria line as it seems to shut quite a bit at the moment.

I didnt realise there was a direct train from crofton park to pancras, that would be great - thanks for that.

I suppose another good thing bout se23 is a proximity to stations on a number of different lines so crofton park can take you right out into kent and from forest hill you can get to croydon where you can go to all sort of place (or get out at croydon and be amazed that people also still wear shellsuits down south too....)