Andrew,
Cadetships are certainly a means to achieving the goal of a seat on an Airliner and I know, train and fly with many of the products of such schemes from throughout the world.
I will tell you this, though- any time a group of pilots gets together, it is those of us who came through the more "Well trodden path" of GA/Bush flying that have the most vivid memories and best tall-tales to tell of our experiences.
As a young Aussie, you have the opportunity to experience a FULL Aviation career, with the advantage of being able to break the expense of the various stages of licensing and ratings up, while hopefully being able to fund your advancement from money earned actually flying.
In forty years time, you can look back on thirty-eight years of flying ILS to ILS in a jet, or have a stash of experience and life-lessons from flying in various parts of the country (or world) before finally getting into the certainly rewarding and satisfying, but none the less rather sheltered world of Airlines.
Go to your local Aerodrome, walk into a flying school, and talk to the instructors there- that will be a good starting point.
Good luck and enjoy it- Thirty two years in and I still do!!