Usually with NHS slt there is what your child needs and what their service can provide and rarely do the two match, esp for asc. Most slt have 1 day asc training. Having had 3 Nhs slts, 1 private slt and aba programme I can tell you only 1 private slt who has some interest in aba has been worthwhile. The others have been pointless. Aba staff achieved far more with language.
NHS slts will write reports based on what their service can provide. It may well be this is all the service is resourced and equipped to do. I am not surprised she doesn't know what to do, that has been my experience of NHS SLT too.
The legal duty to meet your child's language needs lies with LA not NHS. It's the LA who can't have a blanket policy.
If the nhs can't provide a service to meet need the LA will have to buy it in privately - or under the new system you can request a personal budget or direct payments and buy it yourself. This is how we got private SLT by taking charge of the budget and finding a asc specialist slt who was willing to work with our aba team. The nhs slt were not willing to do so because it was so embarrassing how little they knew and it was very obvious when in a room with aba supervisor they were totally clueless
I would say as we did aba they had all the language stuff under control and have far better evidence base for success in teaching language than slt (Cochrane research shows standard SLT methods have little evidence for ASC). We found SLT only became useful when ds got to 3-4 keywords and even now we just use the private slt to advise ABA and do assessments, the language programmes are delivered by aba staff.
So I don't think you have to have a lot of slt input but if you don't you do need to have specialist asc education staff eg in a specialist placement, as part aba programme etc. if you don't have specialist teaching then you would need more SLT. it should be slt specialising in ASC.
I would write up your own minutes of AR as if you ever get near tribunal her report and comments will help you because LA will suddenly pop up saying NHS are offering all kinds of things they never offered before
Find something you think will meet need. It could be a specialist placement or buying in private support to mainstream.
If you have private report you can ask for what that recommended as a direct payment.
Its not too late, locally a ABA secondary school opened 2 years ago and most children had never had good slt at primary and never done aba before and the results already show the children have massively exceeded their previous levels progress in the first year or 2 of getting appropriate specialist secondary provision.
Go look at indep placements, research private asc slts. Find a solution you think will work and then it will be for the LA to prove it can match it which will be uphill struggle with this slt who they could never take to tribunal as a witness
Many SLT will generally believe children with asc can't learn language because they are so poorly trained they have never seen it done. It's easier to blame the child or the disability than blame themselves for being inadequately trained. Our NHS slt told us to give up on DS speaking and said it would be pointless to teach him language as it wouldn't ever be meaningful. We ignored them. He does now speak at 3-4 key words / short phrases. He will need intensive language input for many more years, but I am so glad I ignored them because even a bit of language has transformed his life. Without it he would be much more frustrated and his behaviour would be much more challenging.