Hi Chris,
As far as costs in Australia are concerned I believe it is a little cheaper over there but flight training is EXPENSIVE no matter where you train. Expect at least £30,000 to £40,000 no matter where you train in the world.
As Australia isn't part of the JAA system and there aren't (as far as I am aware so I may be wrong) any JAA registered schools in Australia, I believe you'll be training towards Australia's own licence system which is most probably ICAO compliant.
This means when you come back to Britain you'll have an ICAO CPL/IR etc etc. This would allow you to work on Australian registered aeroplanes anywhere in the world BUT NOT British (G) registered aeroplanes and thus will not allow you to work for any airline etc.
In order to work for a British Airline or indeed a European airline you need a JAA specific licence (its the european version of the ICAO standards). To convert the Australian CPL/IR you'll need to do the following on RETURN to Britain (unless there is a JAA school in Australia):
1) Obtain your JAA Class 1 Medical.
2) Study for and pass ALL 14 ATPL Written Exams. You have to go through the approved residential or distance learning course. Expect around £2500 for this part.
3) Pass your JAA CPL Skills Test (some flight training required)
4) Pass the JAA IR Skills Test (15 Hour Course MINIMUM)
After that lot you'll have an Australian CPL/IR and a JAA CPL/IR and will be able to apply to the airlines in the UK/Europe.
Jandakot Airport seems to be the general aviation airport of Perth so I've done a search for flying schools there and have come up with the following.
http://www.airaustralia.net
http://www.racwa.asn.au/
I am sure there are many others but other people who have actually been to Australia may be able to advise you on those!
Whilst I was searching for flight schools in the Perth area I found the following article on one of the sites:
http://www.airaustralia.net/news.php?id=97
Probably not far from the true reality!
Best wishes,
Charlie Zulu.