Social interactions

I need advice/ideas! My son is 8 years old, I have always noticed he wasn’t reaching certain milestones and from quite a young age I recognised that he may well be on the autistic spectrum - he never got to the stage of playing with other children when he was younger, finds communication with peers difficult and will often avoid etc. I tried to get the school to listen to me about this since he was in nursery and it’s taken until this year for it to be noticed and the school now are making a referral. 

He made a friend in school and they were close, however, his friend has now moved schools last September - they still see each other out of school and FaceTime etc. My son has been upset the last couple of days about returning to school after the aster holidays, he said he has no friends and doesn’t play with anyone, school is different now without his friend and he thinks that is because everyone loved his friend so played with him and because my son and his friend came as one, my son was automatically added into games. This isn’t the case now. 
The whole conversation absolutely broke my heart. He is aware he is different and that he has struggles that others don’t  but just doesn’t know how to begin interacting with other children, he struggles somewhat with communication, his vocab is above the average child his age (school noted that on his referral forms) but when it comes to actually speaking to peers he stutters, panics and ends up shutting himself off. 

I have emailed the school this morning and asked if we can sensitively buddy him up with another child in his class, so they can be encouraged to play together and my some will then be included in games. Can anyone think of other ideas? Moving him to the school his friend went to is an option at this point but with being in the middle of a referral I want to make sure I’m covering all basis first and trying everything to help my son. 

I am my sons safe place, he will talk to me and when we meet my friends who have children he will interact with them but myself or his older sister has to initiate it. 

any advice, ideas or support is welcome!