Loads of free parking around that area on a bank holiday.
Indeed. For a number of reasons (including Fulham away some point recently) we've driven up to South West London on Sundays and Bank Holidays a few times and there's plenty of places to park, both in bays with no restrictions and single yellow lines.
The only caveat I'll add is that we've not done so when Chelsea are at home with limited public transport. I guess that will just mean you may need to go a bit further out though. I'd not be worried about finding a parking space.