Hi Guys
If you want to fly in the UK on a SA PPL it is possible without very much hassle provided your SA PPL is current and same goes for your medical as well.
Most schools/clubs will usually want to give you a check ride before signing you out solo. I know as I have done it.
There is a cracking site already plugged but for the avoidance of doubt its:
www.uksa.flyer.co.uk It certainly answers most questions on this subject
Having spent ages researching the subject I would only convert to a JAA PPL if you intended to start adding ratings to your licence in the UK i.e. Night Qualification & IMC Rating which is something they don't have in SA.
If your ultimate aim is a JAR CPL/IR (Frozen ATPL) and you're doing the modular route then all you need is an ICAO PPL to start your CPL/ATPL course.
Finally on all these threads someone will have had a bad experience with a particular school and yet there will be others that had a great time. Success isn't just about the school but about you.