I went on the TS South Africa trip in September last year - very similar to the JY itinerary in Cape Town. I wanted to experience Robben Island and either stayed on at the harbour or was dropped off after a tour - sorry - can't remember which - brain cell is tired! I just went into the Robben Island centre at the harbour and bought a ticket - couple of TS people were on the same boat as me and several TS people bought tickets on the day for a later sailing.
I am glad I did the tour, which was narrated by an ex prisoner, a personal insight into the life of those interned on the island. The boat trip was fun too! We had a rather elderly boat, the later travellers returned more swiftly on a posh catamaran!
On returning to the harbour I spent some time in the shops - some interesting craft work on display, and then visited the aquarium. When the aquarium closed I asked a doorman to flag down a taxi and was driven directly to the hotel. During the TS tour we were shown where to get an official taxi in the harbour area - plenty available and very reasonable.
As previously stated, "each to their own", but I am glad I took the opportunity to visit Robben Island.
Also - in our case Table Mountain was covered in cloud as we arrived so it was a case of wait and see when our visit could be re-arranged. Luckily the skies cleared one morning and, along with many others, we queued in the very hot sun for quite a while before taking the cable car. It was sunny and hot at the top - but I guess it could be a bit chilly - as usual "be prepared"!
Not long now! Have a wonderful time.