Hi,
Australia is a beautiful country, I lived in Victoria State with my son who is autistic and deaf. To get my son into any of the specialist provision he had to have an IQ of below 56, which as you will know is really low, and he had a much higher IQ.
In terms of ASD at the time I was there in 2010 there was no support within mainstream unless you had MLD as well, as its not seen as a predominant special educational need.
My son went to a mainstream school with 20 children in his class, and one teaching assistant, by in large he struggled but they tried exceptionally hard to include him and educate him. I came back because long term educationally it was not right for him, but had I not gone I would not have known.
Its not impossible to get into OZ with children with special needs, as there was a landmark case over there involving a doctor and he won right to citizenship, so immigration were a little more gentle with our children.
On the plus side I paid for a speech and language assessment over there and it cost 180 dollars and then 1 hours therapy per week was 50 dollars this was also the same for occupational therapy and it was much easier to come by than it is over here in the UK.
My son was also more accepted by the children, for example we lived in a cul de sac and would often have children asking if he could play out with his scooter something that has never happened in the UK.
If its Victoria they provided a good support service through Anglicarevic.org.au my son was able to access after school and holiday clubs and provided one to one support.
You could also look at Department for Education in victoria also. It doe vary from State to State the provision but by in large the education requirements are not dis-similar, also in Victoria on a 457 visa you would be expected to pay international fees as your child has special needs, on a permanent residents visa it would be based on a total expenditure over 5 years and the figure is quite low, I hope that makes sense.
There are clearly advantages to living in Australia, and clearly one of those are that children are really accepted for being children, but the level of educational support would possibly be significantly less than they currently receive.
I dont regret my decision to go over there and it was supposed to be a long term move, but was not right for my son in the longer term. Also since being back in UK which is just over 18 months I am stull arguing for support for my son and finally am going to an educational tribunal at the end of April.
If you want to know anything else or some weblinks let me know, I was working for the state department in Victoria over there, so have some good contacts for you if needed.