Thanks for your replies.
I did suspect the EP report carries more weight hence my post, though it's good to hear they can be successfully challenged like Riven's. Sounds like you go a raw deal there Streakybacon but I'm glad the Home Ed has worked out well for you. And Lou's experience shows you can't always be sure of what type of statement will be offered. I've also submitted a parental report though it was only 5 pages long so hope it was detailed enough.....
The Ed Psych did say once I got her report if there was anything that was factually incorrect she would amend it but if it was her professional opinion she would be happy to discuss it but may stand by it.
DS1's Specialist Teacher is also LEA. She is actually in the process of applying for additional funding for DS1 to increase his 1:1 time from 1.5hrs out of the 2.5hr session to 2.5hrs. This is also to include preparation time for the preschool to put together more visuals as, in her opinion they were over-estimating DS1's ability to understand and were relying too heavily on complicated (for him) verbal instructions.
When a visual timetable was introduced as per SALT advice to get DS1 to do adult-led activities, he responded by becoming disruptive throughout the entire session, each session for 6 weeks. He had previously been quite passive in preschool so this was new behaviour for them to deal with (though it is definitely not new behaviour at home).
They have since dropped the timetable and swapped to a First/Then board and DS1's behaviour has settled though I still have trouble getting him in the door and snacktime is still a flash point). WRT the nightmare that was the visual timetable, The Ed Psych said this was typical behaviour of a child his age, that he was way ahead in many areas and that some children would be starting school with their parents unaware they have difficulties and he wouldn't be the only child who needed help with toiletting and dressing. She also said all parents worry about their first-born starting school.
She dismissed much of what I said about DS1's increasing anxieties as "well you will never know if it is anxiety causing it" and the general tone from her was patronising tbh and I thought at one point she may pat me on the head! He kicked off a bit at snacktime during her visit but she felt this was because he was last to the table, even though he has been disruptive at snacktime for the last few weeks.
I know I just have to wait and see but it felt like she was laying the groundwork for the school to handle with their own resources. As preschool are currently having to give him 1:1 support for the 2.5hrs he is there (though not officially funded atm) I am concerned of how he will cope in mainstream without some specfic support time.