To keep your phone and cameras charged, make sure you have an appropriate adaptor. South Africa uses both 2- and 3-pin sockets. The 2-pins are EU-standard, but most wall-sockets use a circular 3-pin that’s not common elsewhere. You’ll find adaptors at any South African airport travel shop. A portable battery pack is also good for emergencies, especially if you’re travelling to very remote areas that might not have power.
A pair of binoculars is essential for game viewing and a good animal and bird identification book will add enormously to your enjoyment on safari. There’ll be plenty of great photo opportunities too, so if you’re ever going to invest, now would be a great time to buy that zoom lens. Take a spare camera battery and memory cards. You may not have time to download or charge while you’re on the road.