Hi, It was six years ago for us with a child in primary school south of Brisbane. We left Australia and returned to the UK because of the severe lack of support for our son at the time. I think things have improved but based on our UK experience with support levels (we are lucky where we are 20 hours 1 on 1 at high school and getting good grades) I don't think it will be as good as the UK.
Might I add that we love Australia and that it is the only reason we are back in the UK. Our experience is limited to Queensland but after speaking to Austism Queensland they told us there was even less support for adults.
Sorry this is not a more possitive response, we live in hope that things will keep improving so that we can return to the country where he was born.
Good luck, I hope things work out well for your family.