Diagnosed or not diagnosed?

Hi all, one of my boys, 7 years old hasn't been diagnosed as high functioning into the ASD spectrum. Professionals from outside the school have mentioned it to me and as a special needs teacher myself I can identify some of the characteristic. I need advice what should I do? At the moment He has learnt to adapt and when He tests too much in a group at school he moves to another one. He absolutely loves English and reading he finds Maths easy, can see things patterns in numbers although he is not interested in Maths as much as in other subjects. He has many interests and is always into projects as he is very dextrous. I also have found that the school where he goes is not very simpathetic to students with special needs as they are not proactive to identify the students or to provide with help. I also would like to know if there are any groups in North London where my son could meet other children within the ASD spectrum Thanks a lot