You cant junp to the ATPL like in the JAA system you must first hold a CPL, then do the ATPL exams, also remember the ATPL needs you to have a Instrument Rating, so there is another exam before you can jump to ATPL.
Have you looked here at the official website:
http://www.casa.gov.au/avreg/fcl_lic...r/convexam.htm
And I second Nathan at Advanced Flight Training, great guy and great school, his site is
http://www.aft.com.au