Advice

Hi I'm special needs mum first time I recently moved cities and just found out from new school senco my son has special needs more then I expect and should be in special school hes in his last year of primary school they are doing a referral for special needs high school for September hes already been on the waiting list for autism for a year he should be getting accessed this year outside agency's have agreed my son need echp hes also have IEP can someone explain to me what autism actually is please as I thought my son had sensory processing disorder, hes also got dyslexic he also on melatonin for head banging while asleep since age of 2 

I'm looking for advice and help 

Thanks kirsty