I think that CTF is a bit optimistic on driving times. UK flights arrive early morning so you pitch onto the Motorway from the airport to the city in the rush-hour. It is easy motorway driving but just a bit slower! I would schedule 40mins to the President as you have to go right through the city to the Atlantic Coast.
Bantry Bay to Franschhoek is actually 90kms and again you have to come back right through the city. Over 1hr outside peak times maybe 90 mins at rush hours. But again an easy drive - part motorway, part country roads.
Cape Town traffic is not very heavy even at rush hours, but you need to schedule longer then.
Driving from the President to the Waterfront is easy and they do have a huge amount of undercover parking there - at R10 (75p) for 4 hours much cheaper than the UK. Fuel is also a lot cheaper. However if you prefer there is a bus which leaves from right outside the President hotel to the Waterfront. Finishes about 9pm though I think.
CTF has given you lots of things to see. Depends on your interests but I would add Kirstenbosch Botanical Gardens, Cape Town Castle (dating from 1660), the 2010 World Cup Football Stadium and Biodiversity Park. Lots of activity stuff around the city from Surfing (Board and Kite), Abseiling, Paragliding, Sea Kayaking and loads of greatr Hiking - from one hour strolls in Country Parks to serious mountaineering and overnight hikes.
Then a couple of hours drive from either Cape Town or Franschhoek is the centre of White Shark Cage Diving for a unique experience. Unfortunately you sound like you might be outside Whale Season - July-November.
Add to all this loads of nightlife from great restaurants, clubs and bars to theatre, concerts, opera and ballet. Maybe fit in a Sunday afternoon outdoor concert at Kirstenbosch Gardens a great Cape Town institution.
Then you have over 300 wine estates that you can visit within an hour or so of Franschhoek. Great Wines, super restaurants, historic architecture and magnificent scenery.
You will have a great time. Keep asking questions here.