I'm Wandsworth based and had DS at C&W and will have DC2 there in November.
All my regular MW appts were (and are) at community-based clinics, not at the hospital, so it's not the case that you have to go in for every visit. Initial bloods and both scans were at hospital, and my visit to VBAC clinic there, too. Otherwise, have seen my team MWs locally.
Re parking: I've never had a problem parking there or travelling in. When DS was born, my DH was able to drop me off at the main entrance and then parked and met me in labour ward. I had a doula, so was not alone whilst making way to ward. Also, they validate your parking when you go into labour! :) Nice touch. (I wouldn't personally choose my hospital b/c of parking issues, but maybe more important for some.)
As for care, have been happy with all MWs (very hands off 2nd time around, but usual story) and experiences pre and during labour and delivery. After care was unexceptional, but I have heard that from 99% of mothers, no matter which hospital, St Georges included.
Consultants I've had contact with at C&W very good and attentive, too. Also, care from antenatal screening department very sensitive and caring. And VBAC clinic lead MW fab.
Have some experience with St Georges EPU and they are very good there. If you have any issues/concerns before you are booked in at a hospital, go there. You can self refer.
FWIW, I know a couple people who have had very good experiences at Kingston. Not sure if they let you tour wards, though, and that would be important to me.