Holy cow, this board is inundated with bikers from Sark! How many of you guys can there be? Is the whole island out travelling the world on bikes?
A couple of years ago I got my Angola visa in Cape Town. It was pretty easy then, but now the rules have changed and you pretty much have to get it in your home country.
Same with the DRC visa, get it at home and save yourself a ton of hassle. This Christmas, I caught up with Veis in Mali as he was heading south and I was coming north. He didn't have his Angola visa yet and it was a major pain for him to get one and a few overlanders have even had enough problems that they have chosen to fly over instead of spending the time and money to courier their passports back home.
Ghana is another country that has changed their rules and at least on the surface is pushing for visas to be obtained in your home country. A couple I met in Ouagadougou were successful in getting a visa there, but if it's easy and you definitely want to go there, that's another one I would get ahead of time.
Say hi to George for me.