£6 if you sign up to smart parking.
Edit: If anyone does take this route, when you sign up to smart parking the barriers will do number plate recognition and open automatically.
Hmmm ok, bit of a walk from Westfield. Although it is still around the 2 miles from there. The reason I said Westfield is because you car is safe in their car park, I've used it many, many times. Perhaps there is a local supermarket with parking? Mind you I'm sure everyone will have the same...
No idea what the trains are doing, but the quickest way if they have a service is to Clapham Junction, Platform 1 (London overground) or Platform 16 (Southern Fail) to West Brompton.