Hi, I live between Orpington / Chelsfield stations, which have plenty of parking on the streets (especially Chelsfield), however there are no trains to London on most lines between Xmas and new year due to London bridge upgrades. You'd need to go to London Victoria from Orpington, which may influence your choices.
Thanks Loobug, that's worth knowing. Victoria would work so that sounds a plan. Merci beaucoup.