TikkiRo,
RVR Is right, It would be better to complete the Training in ZA, BUT, as far as I know you will still be required to:
Get a JAR Class 2 Medical
Sit 6 PPL Exams (unless you've over 100 hours)
Complete training at the discretion of an approved FTO
and then.....
Pass the PPL Skills test
You should get a credit for the Radio practical and the comms paper.
If you don't want to do that you could fly on your ZA licence on Golf reg aircraft but with restrictions, VFR only, no night, no instrument, no instruction, and VMC only as per the ANO
check out the licence requirement docs on
www.srg.caa.co.uk read GID 21 requirements for the grant of a JAR-FCL PPL Aeroplanes and GID 35 Requirements for the FRTOL.
Good Luck whichever way you choose.
WP