Sounds like a great trip...if the eye-watering cost is not a problem then flying in Australia will certainly be very productive... I can best speak about Perth...The RACWA have a large fleet (many 152s, 172s, M20Js and twins) and many instructors...and the weather is usually great.... However, if you plan on getting an EASA ATPL you should maybe contact the WA Aviation College who are CAA approved for the modular ATPL...they can do the 14 exams and have JAA/EASA instructors...they used to be associated with RACWA...but I'm not sure now...
But if I guess an Aussie PPL is all you need to build hours...and it is relatively straight forward to convert to an EASA PPL when you get back
Good luck!
AQ