Your own vehicle or rental?
4x4 or car, and which model?
The scenic route(wildlife parks,offroad tracks, etc.)or highways?
Time frame.
Camping or accommodations?
Maps, gpsr, or sat phone. the answer here depends on the above.
Carnet or TIPS?
This will help you get thinking.

Have you done a self-drive in southern Africa before? This is a very ambitious trip if it your first. Will there be several vehicles or just one? My first step when planning a self-drive is to start with a lot of research (books and online) about the countries we plan visit. The Bradt Guides to Tanzania, Botswana and Zambia are excellent (www.bradtguides.com). For Kenya, I found the Rough Guide helpful (www.roughguides.com). If you plan to drive Uganda to Kenya to Tanzania to Zambia to Botswana, it would be a long but fabulous trip, and I would be green with envy. I have self-driven through all but Uganda and Zambia, and Zambia is on our list for 2011-2012. We also hope to return (for a self-drive) to Botswana, Kenya and Tanzania that same year. Robin

We are thinking about driving as we can't seem to find any other method of getting from Kampala to Maun that doesn't a}cost the earth or b} be a logistic nightmare/potential disaster on bus/train?

I've drive it a couple times in the 90's, and it wasn't difficult then. Round trip from South Africa. It isn't any kind of logistical nightmare you think it might be. In fact, with the accurate Tracks4Africa maps, it's easy to plan. But you shouldn't ignore my questions.

Just reading your post, and Googled in 'self driving trip in africa' and several self drive sites came up, so you may want to start there and just keep asking questions of those people too. Just thought I'd add that in.