This kitesurfer's travel guide, looks at the Breede River, Witsand, South Africa. It covers the most important info that a kiter would want to know about a kite spot.
I would add two things: it is a ~4h drive there and back from Cape Town so going there and back in a single day can be a bit tiring. You can stay locally but one of my favourite places to visit is not much further along the coast ... the De Hoop nature reserve. The last few kms of the drive there is on gravel road but the drive is spectacular with wildlife and wild birds on every side. At the nature reserve you can book a dinner bed and breakfast package which is quite reasonable (unless you are on a student budget) and the food is to a high standard considering you are at the end of a very long road. The wine list is also amazing and with low markups. I cannot recommend the experience highly enough. See http://www.dehoopcollection.com/Then the next day you either go back to Witsand for another session or head back to Cape Town.
My second suggestion is to take the N1 highway there and back ... the drive is much more enjoyable in my opinion than the N2 as there is less risk of heavy traffic and the scenery is amazing on that route. For bonus points take the small road up to Bonnievale and up to the N1 that way ... the road is planted with flowers either side for miles. I have met guests coming back from that road open-jawed at how amazing it is.