Is exhausting isn't it.
Sometimes you have to get to a really bad place in order for things to move forwards. No help when you're in the thick of it though.
I would make an appointment with nursery with a view to them geting an Educational Psychologist in (they may not be aware they can do this, but they can). Also discuss with them whether a formal 1 session exclusion of your DS would be appropriate, especially as they're doing this unofficially anyway. I think they need to contact the council to do an exclusion and produce an evidence trail of why. It may be something that flags things with the council SEN but hopefully nursery would know or be able to find out if this actually could be a good way forward.
With any diagnosis what you need is paperwork to evidence behaviour. Both the Ed psyc and speech and language will produce you paperwork. A behaviour diary for home and the same for nursery a sort of home/ school book with a daily/ as necessary comment on behaviours outside of age appropriate norm can help as evidence.
I would also go back to the GP and see if they will refer direct to speech and language for social communication issues. Are there any physical challenges your DS faces like slightly odd run or difficulty/ resistance to holding a pencil/ cutlery? If so you could ask for physio and occupational therapy assessments too. (Yet more paperwork for your evidence pile)
With the school some of the questions only they can answer. 1-1 wont happen straight away. Nursery can provide you with a behaviour report to talk about how they manage and specifics of tasks/ activities your DS needs extra support with i.e. Morning integration/ taking coat off. Engaging into activities, toilet, eating etc.
Statements got replaced last year with Education Health and Care Plans (EHCP's). You can apply to your council direct for one. Nursery could apply in parallel for you.
If you go this route, its certainly one that could get you in the assessment process, get support on the special needs boards because you need to evidence that you meet the threshold for assessment. If you achieve this your DS will then be properly assessed with a view to getting an EHCP which will call in all the services you need to see him (you can list those who you feel ought to be involved). The problem is all statements are currently being transferred to EHCP's and staff are even more overworked than normal.
School funding for additional needs children in schools changed last year so the first so many hours of support they need to supply direct before applying to the council for a top up of funds for higher needs children. What do you feel your DS needs?
With DD I've asked for, and been offered, extra just us sessions to visit the classroom, school environment and teaching staff. We're already going into family assemblies every few weeks to see the school environment and so DD gets used to the routine etc.
I've also asked for help with going in in the mornings. We'll try the line up but if she struggles we'll go in either first or last a few minutes after the initial bustle. I've asked with support with integration into tasks. Shes very resistant to joining in but if shes led to an activity and physically shown it she engages (which I appreciate is different for every child). We're initially going to have weekly brief feedback meetings to monitor integration.
If they do have to differentiate any work i'll be asking for an Individual Education Plan (IEP) these document and differences and have an action list as to how they're going to be worked on. They get reviewed regularly and as they have an action plan and outcomes chart progress well.
Any way. Happy Mothers Day. Don't try to keep it all in. Its tough and you really aren't unfortunately alone in going through this. Sometimes laughing with others about the ridiculousness of some of it really relieves a lot of pressure.
some light reading for you