When my DS2 started primary school it was something of a relief not to get drawn in to all the petty worries I had with DS1. The Reception teacher was one of those who came out of school each day with some minor problem or other a child had had, eg not sitting still on the carpet, playing with the taps in the toilets etc. I loved it with DS2!
If she came my way and told me about his behaviour that day, I could just say, 'Yes he does do that, doesn't he? Good luck with it!' (and laugh quietly)
He had appropriate 1:1 support, (very important for him) so what could I do about it? Obviously I did lots at home but it was still a great relief to realise I couldn't care less if he couldn't sit still on the carpet, etc. Lots of NT boys (and girls) couldn't either, and their parents worried loads. That was a classroom management problem, not a parenting problem. He wasn't being teased, he was happy, he was learning, he was obviously different to the others but the children were really good with him.
I think the fact he was my second helped me tremendously. I'd done a lot of pfb crap with my pfb (like the mother above and the 'wrong' class issue) and realised that there's no point worrying about the little things. The problems are sometimes with the other parents who still do worry about the little things, but that's another story. (Like being in my DS's set for Maths etc.)
Not to say that some of the 'little things' aren't important. Being accepted and included is important, so getting party invites (occassionally) is important, going to after school clubs was nice, even if it didn't happen for a few years. And there have been problems along the way, of course. I try to fight one at a time and not look too far into the future.
DS2 is about to go up the secondary now, which brings a whole new set of worries, but nothing is so scary as letting them go to Reception.
Good luck to all your lovely DC starting in Sept. Don't let the bastards grind you down!