Funny you should ask as I've introduced a new attraction at ADVENTURE OVERLAND entitled "Bush Mechanics". It's one thing repairing vehicles in a proper workshop, another matter entirely fixing a dead motor out in the boonies.
Sponsored by Frogs Island 4x4
of Abingdon in Oxfordshire, there will be a host of mechanics on hand to give tips and advice on the best way to keep your steed rolling when on the road ... or off it!
As for courses, there's a guy I know of called Dave Gunning who runs exactly the type of African-based coursed you're seeking here in the UK. You can find him here:- www.bushmechanics.co.uk
Don't know I know the guy personally so can't say whether his courses are good or bad. Put it this way, I've heard nothing bad about him, so that has to be a good thing. Still following?
What I'm trying to say is, bad news travels really fast in the 4x4 community, so I'd say that 'no news is good news' in this instance. Contact him, what have you got to lose?