Hi Lynda
I'm on this tour in Oct, I too was very confused but I've just booked the excursions we can pre book.
While I was on the phone I did ask the same question and she said for booking excursions when there that, the South Africa excursions will be payable in Rand and the Zambia (if your doing the add on) will be payable in Dollars or sterling! They will not be able to take card ::(
But they try and book very quickly I hear, basically as soon as you land lol. So your not carrying to much cash around
A few of them clash so you might be able to do all of them.
Hope this helps.
Have a wonderful time, please let us know how you get on and any advise
Chloe xx