EHCP assessment with Paediatrician

Hello my 12 year old son is undiagnosed with ASD/SPD, he has been seen by CAMHS psychologist and he has now been referred to Cheyne development hospital for assessment for ASD with a six month waiting list for first appointment, we have also Been approved for Educational plan assessment, the assessment is on 25th of this month at the same place where he is waiting for his diagnosis , I am not to sure what to expect. 

Thank you