If you have more than 100 hours as pilot of aeroplanes and your Oz licence and medical are current and valid in all respects, my understanding is that to obtain a JAR-FCL PPL(A) all you'll need to do is to do the Air Law and Human Performance exams (plus the FRTOL exams if the CAA won't recognise your Oz RT licence) and pass the PPL Skill Test.
Alternatively, why not just fly day, VFR and in the UK on the privileges of your Oz CPL as it's an ICAO licence?