Mole, you are understandably scared of the unknown. I was you twelve months ago.
I went from having a 7 year old son who was a bit quirky and sometimes hard to handle to having a child that was diagnosed with ASD at his first appointment with the Paediatrician.
You have had some great advice on here so far.
Its great that the school are on board and want to help, as that's half the battle really.
As Arsenic said, nothing has changed, your little boy is still the same little lad he has always been. The reason he is so moody and unpredictable at the moment, is probably because the transition from infants to juniors is particularly tough for children on the Autistic Spectrum for several reasons. They are suddenly expected to organise themselves rather than having a lot of support and assistance from teaching staff, their peers are maturing quickly and social structures in both the classroom and playground are changing and that's without even thinking about the harder work etc. As a result their anxieties build up and up and they find it harder and harder to cope.
My ds spiralled downhill in year 3 and our school were hopeless. He had very little support and what he did get we had to fight for ourselves. You won't have to do that, as the school are right there with you from the sound of it.
Fast forward to now, ds has just entered year 4 and is doing so much better than he was in year 3. We have support from the Autism Inclusion Service and the Educational Psychologists and I have today had a fantastic meeting with the school where they have agreed to all manner of other things to support him, including developing/nurturing a small social group of friends who can help him with his difficulties with social communication.
If you had told me this time last year that my boy would be happy and coping well in year 4, I would never have believed you. Things aren't perfect, we still have hiccoughs and problems here and there, but we are moving in the right direct and I can see light at the end of the tunnel.
I also wouldn't have believed it if you'd told me I would know as much about ASD and the Special Education Needs system as I do, but it all comes in time and you learn a little more every day.
I would recommend doing as much reading as you can around the subject.
There's lots of useful stuff on the National Autistic Society's Website here and would highly recommend reading Tony Attwood's book The Complete Guide to Aspergers as well as Brenda Boyd's books Parenting A Child with Asperger Syndrome and Appreciating Asperger Syndrome. They are the ones that helped me to get my head around things the most.
Oh and keep coming on here and asking questions. It is a lovely place with heaps of support from really lovely people who not only care, but also understand.
We went via the GP to get a referral to a Paediatrician, who then referred ds to the local multi-disciplinary ASD assessment unit. He is due to reach the top of the waiting list for his assessment in April 2011, but that hasn't stopped him getting the support he needs in the meantime.
Hope that helps a bit. 