Consider going to NZ, as they will recognise your RAF experience, and will allow you to do far fewer exams (I think 2, instead of 7). Much the same for recognition of your IR.
You then get a NZ ATPL/CPL, and use what is called the Trans Tasman Mutual Recognition Agreement to trade in your NZ licence for an Aus one (paperwork exercise only).
Details of what the Aus and NZ CAAs will recognise from your RAF career are set out on their respective websites.
Bear in mind though, that if you decided to come back to the UK, you'd need to do all the UK exams if you wanted a UK licence...