Coolchet
Alot of good advice from some obviously experienced people. My advice is contact your main GA airport from wherever you live (Bankstown, Archerfield etc), ring up the schools and charter companies and ask them. If the first couple of places you ring can't help you DONT STOP!!! Ring more places, you will definately find a place that can take you in. Aviation is all about contacting people, knocking on doors and asking. Regardless of what company you get work experience in, you will get the opportunity to learn more about our industry.
I did my work experience in 1997 (when I was in yr.10) with Brian Westin at Southern Skies Aviation. A great guy and he not only taught me alot but also opened up the door to the world that I am in now.
People and companies that take on work experience students are usually people that have a passion for aviation and are keen to pass that on.
There is always room in this industry for bright, hard working and determined people.
Good luck and enjoy.
Eternity.