Parking: me and the ex (who lived in Southampton) whenever we went to shows at Brixton, we would drive to Richmond and park up at the BIG (and free back then...4 years ago) car park just the other side of the main shopping street, jump on t'tube on the District line all the way into town. For Brixtaaarn, change at Victoria (which you probably well know already), Vic line all the way to Brixton...AND as far as I am aware...its working again!!! But dont hold me to that.
Up until other week, Brixton UG (Vic Line) shut at 10pm. V annoying at the time. :(
BUT BUT BUT...v recently ye Olde District Line from Richmond has been ridiculously stupid...aka NOT working at weekends! BUT if it is, and you's guys are coming up from Portsmouth, t'would be a good place to park up...and v easy to get to from the (M3?) and leave from the next day for a speedy and easy return home (no travelling by car through London needed!) (AND...dare I say it.doable following all nighters in London! ;)
PS...I still dont have a ticket for the show...kinda brassic but may have to pull out the stops to join you on Sat (despite the fact I am working the next at the museum).