I can't say much about warmer waters in south africa, only been west of J-bay, really.
Generally, for surfing around Cape Town: The water will be cold, make sure you pack a winter wetsuit. Things should get warmer
as you head towards the Indian ocean.
I didn't surf nearly as much as I had wanted in south africa, but I really really loved "Kitchen Windows", which is a wave in J-Bay (but not the famous bay). Plettenberg Bay was beautiful / scenic, and felt a slight bit "posher" than JBay (not sure what the actual accomodation prices are), surf-wise the places in PBay I went to were closing out & pitching me, but that may have been due to idiocy / conditions.
I have heard great places about Buffels Bay, too - it's supposedly a fun wave for intermediates.
In Cape Town, Big Bay can be fun and has a beautiful view of table mountain from the lineup. It was damn cold when I was there, tho. Kommetje was beautiful and fun; Muizenberg was onshore every day I was in CT, so I didn't get into the water there.
I have to admit that psychologically I could never get over the ... errr ... wildlife in the area, e.g. each time anything moved in the water
I was convinced I'd get eaten by a shark, but that's mostly me being panicky. Do
pay attention to the shark flags in CT though, this year
has been sharky.
Cheers,
Thomas