Just got a life...
Here's the other side of the coin.
Finish off your JAR licence, start instructing like you say and get into a job flying a jet in the UK or Europe.
I did contract flying in Africa for best part of 6 years and it was great. I would not trade the time in for anything, but you must understand you are only delaying the inevitable.
You obviously have the right to live and work in the UK(guessing) since you have done the JAR theory exams. So, if you do go and fly contracts for a few yeas, it is a job and lifestyle which has a shelf life and you will have to come back to the UK in the end.
The market is booming here in the UK and Europe, and for your 3 years in Africa geting to fly the Caravan or BE-200 or B1900 you could be missing out on unfreezing your JAR ATPL which is what is going to get you a good job.
I think you have to look at it from a long term and financial point of view, and going to fly in Africa is just delaying you getting to a well paid job.
Contract flying is on Caravans, King Air's and 1900, in the UK you have the opportunity to get on to Dash-8's, ATR's, EMB 145 and others, B737's and A320's with low hours.
You have already tried getting a job in Africa and with no luck, you are also at a huge disadvantage as a low houred pilot without South African nationality.
Just a few thoughts to consider, since all the replies so far have been in favour of going.