Hi Janice
You will be able to use a credit card for some of the optional excursions on the Zambia part of your holiday, subject to a handling fee of around 3%. Your Tour Manager will be able to provide you with further details.
However, I'm afraid you will need cash for any optional excursions you want to take in South Africa, so a good money belt might be your best option. It might be a good idea to take some travellers' cheques and sterling as well.
Kind regards
Olly, your editor