Kalk Bay is easy to get to whether by car or public transport. From the airport take the N2 direction Cape Town. Keeping left take the M3 direction Muizenberg( Left off ramp).
Follow the M3 until the end then Turn left at the intersection. At the next set of Traffic lights turn Right. Drive about 150m then Turn Right into Boyes Drive( mountain road).
Follow Boyes Drive direction Kalk Bay. Take the 2nd Left into Anderson Road and then the 2nd left into Gatesville Road. Castle Hill is the big white building at the end on your left.