A few years ago now but DS initially got 1:1 funding for 12/15 hours (in practice the nursery made this up to 100% themselves). He got 2-3 visits from SLT over about 9 months who gave 'advice' to the nursery but didn't design any programmes. He saw the early years teacher once who gave the nursery very basic 'advice' to 'keep them going' until he got his diagnosis.
After diagnosis the autism outreach team went in and gave more 'advice' mainly simplistic stuff like taking pictures off the wall to make it low stim, buying him a pop up tent and using visuals (none of which he responded to because he was so withdrawn and passive, he avoided the low stim area as has few sensory issues). Outreach said they would go weekly but actually went 2-3 times, then the person left and no-one went again for months.
SLT and autism outreach spent several months arguing whose responsibility it was to teach social skills with the result neither ever did (apart from constantly recommending turn taking practice)
We paid privately for ABA consultant to train us and we worked with him at home and paid for ABA to provide some advice to nursery - which they found far more useful. We also applied for Statement (now EHCP) right at the start and after 15 months and 2 appeals won a full-time ABA programme at tribunal by comparing what we had achieved at home via ABA and how much more useful the nursery found it - to what the statutory services had provided.
we bought the nursery books e.g. More than Words Hanen to give them ideas.
None of the advice from SLT or autism outreach was anything you couldn't read in a £5.99 intro to autism book. It was very basic awareness and strategies. Autism outreach was heavily criticised by the Tribunal for not putting in robust programmes of intervention themselves.
Some families (whose children were not in nursery) got weekly portage visits which they found more useful than SLT/autism outreach and indeed many of them put off getting a diagnosis so they wouldn't lose portage and have to transfer to autism outreach.
I would suggest you look at Caudwell funding and pay for some private input (I think they will pay about £3000 to get started). Yo can then use this to train yourselves and the nursery to implement interventions (could be ABA or other approaches). ABA can be expensive but we managed with 2 hours supervision a week (£100) by using DLA and family contributions until Tribunal. There are other charities (see ABA4ALL Facebook page)
Cerebra used to offer grants for private SLT of about £500.
PEACH and Ambitious About Autism run intro to ABA courses for parents
My advice would be to train yourself. We wasted several months waiting for the services to come in and then were profoundly disappointed when they did! They were not worth waiting for.
Sorry to be so pessimistic but I wish someone had told me not to wait.
I would apply for EHCP now. You probably will be turned down first time but often back down when you appeal and something like 97% of appeals for an assessment are successful. You do not need a diagnosis to apply.