What type of support should I expect for my 4 year old ASD child in mainstream school?

My child is currently nearing the end of his reception year at a mainstream primary school. We are currently going through the ECHP process. My child currently only attends school for 2 hours in afternoon due to concerns from the school he would not cope with a full day. He has designated TA who is reportedly specifically for our child for constant 1 on 1 support. I have no experience in parenting a child with ASD, but I was under the impression once ECHP had been approved and put in place, this may unlock more targeted support. However at a recent meeting with the SENCO they stated they were already provided the highest level of support by providing 1 on 1 TA. And the ECHP would simply provide them funding to provide this 1 on 1. Is this correct? Or should there be options for more specialist support?