There isn't much hassle with a UK PPL in Oz. I can't remember CASA's webby off the top of my head but it's very informative re licences and so forth.
With regards hiring an aeroplane, shouldn't be too difficult. You may need to do a check ride of some sorts just to keep the insurers happy. Trust me, either get a GPS or make sure your visual nav skills are up to speed. There is a lot of Oz to get lost in.
Having said that, pick somewhere interesting and challenging. Flying up the coast is too easy.
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reddo...feral animal!