We are back. We had the most amazing time. For the benefit of anyone thinking of doing this in the future:
They will tell you to wear neutral coloured clothes. This is not necessary. You are in a vehicle, you are not sneaking up on beasts in the wild. Comfy clothes and very comfy shoes -- I recommend Birkenstocks, because you are standing in the vehicles on the game drives.
Bring cash. The guide, and frequently hotel staff, get tipped in cash. Also, optional side trips are usual cash affairs and there are not a lot of ATMs on the savanna. US$, Pounds Sterling, and Euros are widely accepted.
Bring a really good camera: yours or someone else's.
Prepare for weather that ranges from cold and damp to hot and dry.
If anyone has questions, please feel free to ask.
edited for readability