I can only speak of Kenya, work permit...work permit...work permit.

If you arrive in Kenya with a UK JAA CPL you will have to sit a conversion exam, do a medical and an initial instrument rating which would involve (as far as I know, not sure how many hours) training to prepare you for the test and the test itself.
The real sticker here is the work permit, almost impossible to get for pilots these days.
I'm busy doing it the other way around at the moment and I have done 14 written exams, FRTOL and a medical. Next stage is a typre rating and hopefully after that the green book.


You will need to look carefully at the requirements for licences and make your decision, if your idea is to work in Africa for a few years before returning to Europe to build experience, you may want to consider a South African or an FAA licence (same conversion but probably less initial financial outlay and some cash in the bank at the end of it!).
If you have sufficient experience you will not be required to attend a full time ground school for JAA, but you will still have to sign up with a ground school provider as they have to endorse your written exam bookings, I used CATS, a friend used Bristol both got us through.
A small advantage of the JAA is that although you have 18 months to pass all the exams, (12 months to do the FROTL from passing ATPL IFR/VFR Coms without writing any more exams), once passed, you have 3 years to get your licence issued which is very handy for accumulating the ever required spondulics!!
If it looks confusing it's probably because that's how it looked to me initially but once I got going it has followed the format mentioned above and you just have to tick the boxes. If all goes well next April for me it will have taken me 2 years from start to finish!
Good Luck with it all