Llandudno beach (map) must be one of the most beautiful beaches in Cape Town, so if you're prepared to brave the reasonably steep and narrow residential roads and happy to contend with the distinctly limited number of parking spots, then you have to make this beach part of your visit to Cape Town.
I believe also that Llandudno is also an awesome place to surf, and not only because of the easy-going waves, but also because of the beautiful mountain and beach view that you have when standing on your board. It's simply breathtaking.