I live a little further south but can tell you that U.S. dollar is king, steer clear of local currency if you can. There is probably three different rates when paying your hotel bill, for visitors like yourself from the UK, for locals and the South African rates ... Zim (Zimbabwe) has much the same set of rules, but be aware they have just devalued yet again and U.S. dollar the only currency that'll work (SA rands a good and safe alternative). Be sure to take prophelactics (for malaria) even if they make you feel nauseous(?) stick to the regimen. Don't walk about like a tourist (have a camera swinging around your neck) rather be ultra streetwise ... and you'll have a great time. Good luck ...