I send my ((hugs)) too, it's quite a shock coming to terms with the diagnosis and at the same time taking on board all the information everyone downloads onto you. There's a lot to learn in a very short space of time. It will get easier as things fall into place and a routine sets in.
My daughter was diagnosed at the age of 4, it sounds like about the same time as your son, she had started reception year in the September and she was diagnosed in the October.
Our school on the whole have been very good about Jess' diabetes. We did have one teacher who we were not very happy about, that was her reception year teacher but after talking to the head and raising our concerns we never had a problem with that particular teacher again. Some years Jess' diabetes has been looked after primarily by the TA and other years the teacher seems to take full responsibility.
So far Jess has never needed staff to do injections for her. Initially she was on a pre-mix insulin which meant an injection in the morning at breakfast time and then nothing until the evening meal. It worked okay, it was nice in the sense that there was no injecting to be done during the day, but the down-side was that she HAD to eat lunch spot on time otherwise she went hypo. Now that Jess is on a basal/bolus regime I go into school to give her lunchtime injection. The school did offer to do that for me but I prefer to do that myself until Jess can take over on her own. I work from home and our school is only a 5 minute walk away so I can nip out at lunch time to take care of that. If I'm not able to do the injection then my husband works very locally so he can take a bit of time out of lunch to get over to the school to do the injection.
Jess is 8 now and we've never experienced a problem with me being there in school for Jess, no children have commented about me being around at lunch times and Jess loves seeing me in the middle of the day. I do help out occasionally at school on activity days so it's not unusual for children to see me or another parent in school. I think most primary school aged children are quite accepting about how things work. I suppose when she's older she won't want me at school but I'm hoping that by then she'll able to do the injecting herself.
Blood sugar testing has always been quite easy. The staff at school were very happy to do it and it wasn't long before Jess could do it herself. We always ask staff to check with her what the reading was incase it is low and for some reason she hasn't been able to communicate that.
Our diabetes nurse has visited school a couple of times now to talk to teachers and TA's about diabetes and how to manage Jess at school. She was especially helpful in the first year when I was still learning a lot myself, having the nurse to explain things well and to be able to answer questions I possibly didn't know the answer to was very useful. When she has visited the school they have included a number of staff members in the meetings. Usually two or three TA's and one or two teachers, although think of it now I'm sure they were all first aiders too. It's so that if a member of staff is away or not available there are others in school who know about Jess and how to managing things.
There is another thread in this board where I have posted a link to an australian website where they have a booklet available in pdf format. I printed that off this year and have given it to Jess' teacher as I feel that it explains T1 diabetes so well and is particularly aimed at providing information to schools. I hope that someone in the UK will produce something similar.
[see:
http://www.diabetes.co.uk/diabetes-forum/viewtopic.php?f=16&t=8947]
I've read that some schools are better than others with managing T1 in school. My only advice is that if you feel the school aren't being helpful, your best bet is to try and get the Headteacher and the SENco on your side, I think without their help you are fighting a losing battle.