Referral nerves

Hi I'm new here.  We've recently had a diagnosis of Aspergers for my sister at 35 years old. My 13 year old son is a mini version of her and always has been very clever but socially he struggles. As he is hitting puberty things are starting to become more apparent and he is struggling more and more, saying he can't cope at school even though the teachers have no issues with his work or behaviour , he constantly talks about his interests and repeats whole books to us or how to play computer games, he gets very anxious when out and will shy away from noisy areas, so I've now got an appointment for him with the gp to ask for a referral to camhs. My query is what can I expect from the gp? I've been keeping a behaviour diary and have looked up resources on the NAS website armed with these (I know she won't have time to read it all) is it likely she will put the referral in ?we've been before for suspected anxiety when he transitioned to secondary school but another other gp said he was just a sensitive boy and my son has taken offence to him as he sent him out of the room to discuss his thoughts with me, son also convinced they won't believe him. Any advice on what we can expect at the appointment and time frames for camhs would be greatly appreciated.