Your DS sounds developmentally about the same level as DS (nearly 6, Yr1) he has 35 hours of ABA per week, 48 weeks per year won at tribunal. He is making good progress with social / language despite severe deficits.
Herts are right, what your DS is getting is 'usual' for many LAs, in my LA they justify it by saying provision is 'equitable' - BUT the law says your child's SEN must be met and every one of his SEN including social. When told by the LA its not fair my DS won this and other child don't get it, my response is to say that the other children need it too and the answer is not to take it away from my DS but to also give it to the others - why should we aways be told to level down not level up?
SALT may have a maximum, but that is a maximum of what their service can provide, not an indication its the maximum a child could possibly need. if your child needs more the LA must buy it in privately.
Interestingly at Tribunal the Panel also gave us half termly direct and indirect SALT which we did not even ask for on top of the ABA.
I would also agree with Star in that NHS SALT and LA outreach IME do not know how to teach social skills or even language to children with autism, without exception every one of their suggestions achieved nothing for DS, which is why we turned to ABA
So I suppose I would say go for the statement and know a Tribunal will not look on the current provision as appropriate and you will win more, but consider whether more piss-poor SALT and outreach is really worth the fight. You may be better asking for specialist support - DS has ABA come into mainstream, private ASC specialist SALT is another option, dual placements, indep special schools etc. The downside is you would have to fund some private SALT or ABA yourself to show it will work for your DS in order that a tribunal will award it. You could perhaps if you could afford to buy in some ABA help after school and do playdates etc to work on social skills.
I would also video him from now on to show his level of language, social communication etc as its amazing how children suddenly improve on paper when you criticise the provision.
If you pm me I can send you a copy of DS statement which lists all his objectives and provision - much of which would be what your DS would need. It might help you know what to ask for on the statement.
By the way nothing you have written yells LD on top of autism. Severely delayed language and social skills are entirely consistent with autism on its own - DS is very bright, but his deficits in language / social are very severe and need a lot of intervention to achieve the progress we are seeing.