"Late in September 2009 Tom Picton and Carl James will drive from Buckinghamshire, England, to Die Hel near Cape Town in South Africa, then attempt to drive back home."
Guys, that isn't a lot of time to prepare a vehicle properly if your starting from scratch now, even if you have the next two months to do it fulltime, especially as many people are on holiday for a few weeks here and there at the moment etc.
My advice would be to spend your money on the mechanical side of things as the first priority, as these problems are the least fun to suffer along the way: Start with things like a new clutch, new timing belt, replace all rubber bushes/hoses/rubber everything etc etc
Good luck, your going to be busy, but the impression from your website and posting is that you need 3 times as much time to prepare (assuming you are doing so from scratch) else your first 6 months of the trip could be a comedy of errors that could have been prevented with good preparation.
I'm not trying to be nasty or damper your enthusiasm, but I have seen a few similar sites and projects over the years and they all seem to suffer from a lack of good preparation - the trip becomes an endurance of easily avoidable hassle imho.
I hope you have already proved me wrong and have a safe and happy trip though!