Glad to hear that your team are going to the school with you.
As they already have others with T1 in the school, they will have appropriate plans in place.
It is important that Dylan is able to manage his diabetes how he feels comfortable. This may change as time goes on. I was teaching when I was diagnosed and at first I took up the offer of an office in which to test and jab before lunch, however I then switched to just getting on with it in the canteen.
It is important that he is not expected to leave the classroom to deal with hypos. He needs to have his kit with him and as
@trophywench said he needs to be able to test and treat in situ.
Has he spoken to any of his friends about his diagnosis yet? It will be good if at least a few others that he is with know what is giong on, so that if he has a hypo between lessons someone can stay with him.
I am going to tag
@Sally71 who has a daughter in secondary school who may be able to offer some tips.
A lot to take on board, but it sounds like you have a good Diabetes team. If you have any worries just ask. That is why they are there.