Not much point for this post, but I have been waiting for DS1s formal AS dx report before asking school for extra support for DS1. Have now seen the report (in draft form so some changes needed) and spoken with the dx team about it. They are going to send in a specialist ASD teacher in to make more recommendations than are in the report (there are a couple of pages in the report already).
Anyhow, was talking to DS2s nursery teacher (who happens to also help the SEN pupils in the school who are on school action) about DS2 when DS1 came up in conversation. She has now added DS1 to the SEN register and is going to give him extra support on social skills, along with giving him a bolt hole etc, is even looking forward to the ASD teacher coming along and giving them more help!