Hi Luked,
Australia is a little sparse when it comes to Freedive Instructors. There is one guy called Erez Beatus doing courses somewhere up around the QLD border but I have heard he's been overseas for a while.
I live in London but i'm moving to Brisbane around Oct time, i'm an AIDA Freedive instructor and will be starting courses sometime after October. If there is demand then I can certainly come down to Sydney - I lived there for 8 years before heading overseas so i've got plenty of mates to catch up with there!
I will be teaching AIDA 2* and 3* courses, you can see some details on the
AIDA International website under Education.
Cheers,
Ben