3yo with potential ASD

Hello there! , i have a 3 year old soon to be assessed(and maybe diagnosed) with ASD ,  he is non verbal and he is very delayed pretty much in all aspects. He is a happy boy and ofr the most part easy to work with (goes to the park, nursery , likes the car , can sit at a restaurant etc)

Now what I'm after is real medical support on his communications (we normal get someone to visit us and tell us how delayed he is but not real help) , i see online that in the US there's clinics (private mostly) that have 1 to 1 classes and help of that sort.

Is there anything like that in the UK , it seems like the support we get through council and nursery is a bit short so I am willing to go privately if there's something available ,  i live near Leeds but I'm willing to relocate if needed.

Please let me know if this is something that exists in England , as most of the websites i get served by ads look quite un-professional