Eureka, thanks so much for those tips and links - I had avoided searching with the word 'kindergarten' because over here that is ages 3-5, but wiki has instructed me that it is different in the US, so there is lots more info than I thought! Great.
Sweetleaf, I'm sorry to hear about your experiences. I don't know how my son will cope, but will get him as ready as I can, as I think he will be keen to go to school (he wants to go already!). If it doesn't work out or we think he isn't ready at age 5 then we can delay until age 6, which is a comfort. We also have a local school with a lot of experience in autism so I am crossing my fingers...
Gnomey, it's daunting thinking of life without those services, isn't it? We don't get a classroom aide at the moment, but our OT and SLT will stop at age 5 I think, regardless of whether DS goes to school then or not. But I am paying for a fortnightly private session of SLT as well, as although DS's language is actually now deemed age appropriate, he has so much to learn in terms of attention span, concentration, turn taking, listening, sitting at a table etc etc. *sigh* will a year be enough?