Now booked :) Some info from the website:
Dress in layers, Warm weather jacket, closed shoes, beanie, scarf, hat/cap, polarized sunglasses, towel, bathing costume( it is a good idea to put this on under your clothes prior to boarding), sun block and camera.
Sea Sick tablets -.We recommend “Sturgeron or Dramamine” tablets. Take one the night before your trip and another one and a half hour before we are scheduled to meet.
Lots of places you can do shark cave diving around Cape Town. I think you have to book in advance to be sure.
Cost might be between £100 and £150, which is for the trip and dive itself. I think you can do a shark spotting trip for less than this which is basically a trip where you see sharks and hopefully see them 'breach'.
Might be able to tie this in with a visit to Hermanus.
Shark Diving R1200-R1300 (Approx £100-£110) per person (full day), location: Gansbaai (near Hermanus)
The Apex Predators link below is interseting because their page points out the other things which are nearby. It suggests that they run their trips in the morning and evening (presumably fairly early morning), meaning you can still have the rest of the day for other activities. From their website (with bsome bits highlighted as they are important):
We offer two tours daily in either the morning or afternoon, this means that your shark cage diving experience will not interfere with other activities you may have planned. We are located in Simon’s Town, which is just 45 minutes from Cape Town & close to oceanic areas that provide the best shark cage diving in the world. The famous Boulders Beach Penguin Colony is just five minutes from our launch site and Cape Point Nature Reserve is 15 minutes away, so plan to visit these famous attractions before or after your shark cage diving trip. As seen on ‘Planet Earth’ and ‘Air Jaws’, both filmed from our vessel, Seal Island is world famous for unique activity where the sharks breach out of the water. Apex predators offer more than shark cage diving, our area offers the chance to see breaching (sharks jumping out the water) and predation (sharks hunting seals). This happens most frequently at Seal Island, and June, July and August are the peak months for seeing this behaviour. If this is the type of activity you want to see, book your shark cage diving trip during these months. Besides natural predation and breaching, we also offer shark cage diving on our trips in South Africa. You can therefore have the possibility to see and do all three in one shark cage diving trip. This is a great opportunity to experience all aspects of Great White shark behaviour and witness these creatures in their natural habitat. All shark cage diving is on snorkel so a dive certification is not required. We specialise in small groups and take a maximum of 12 guests per trip with four guides on board. In not such great news, November isn't a great time to see Great Whites, although I think you still have a chance (and you get to see other marine species anyway)
Not sure whether you just book the trip itself and decide on the day whether you want to do a dive...
Also not sure whether between Sept and March you do the trip from Gansbaii which might be further from Boulder's Beach.