Hi Laura
Possibly the best spot in SA is Waterval Boven - with over 500/600 sport climbing routes. THe weather is cold but stable, in winter (May-Sep) it drops below freezing most evenings, but rain is very scarce in winter. Daytimes are great for climbing once you thaw out of bed.
check out the wiki on this website - waterval boven - it has the new routes only. the route guide is out of print but there are always many people there to ask, and the local guide company is very friendly (Gustav and Alex) and you could borrow a guidebook I'm sure. camping is cheap (R50/night/person(Dont know where you are from? abot 7USD/person)), and chalets available at tranquilitas campsite for a bit more.
http://www.rocrope.co.za or climb (at) rocrope dot com
Good trad in vicinity as well - within 2 hours or so. some nice trad routes at waterval boven as well.
shout if any more questions. We're in the area but moving soon!
Ray