support with medication

Hi,  

I'm really confused, my Son was really struggling with sleep, focus, and anxiety amongst other things.  We've been attending sleep clinic, GP, counselling and were told to get him assessed for Autism.  We were recommended to try Melatonin to help him sleep and were told that the only way to get it was through prescriptoin and that he would need a diagnosis.  We've now had a diagnosis confirming autism and ADHD but Melios couldn't advise on how to go about getting treatment or medication and said to go back to the GP.   The GP already told us he can't prescribe Melatonin and he told us that we would need to work out the meds with Melios.  Can anyone advise who we can speak to for a prescription?

Thanks.