In Cape Town there are many good bouldering areas:
You'll need a car though or, best, if you can hook up a guide to show you around:
Out of the city:
15min drive from city - biggest area and best!
30min drive from city - concentrated but far to travel!
In the city:
A group of boulders with no walk-in, near Newland Forest
Small area on Table Mountain near Cable car
Next to beach, cool spot for an afternoon
Check out:www.cutloose.ca.tt and www.bouldering.co.za