Provision for SEN Inclusion Funding in cross-county border situation

I could write war and peace on this so apologies in advance!

I have a two year old son who has Down Syndrome. Attends an amazing mainstream nursery full time who are fully supportive of him. Now he is two he is due to move to the next room, but his complex needs and lack of mobility means he needs additional support, and the staffing ratios in the room will not allow for them to give him almost 1:1 care, which he gets now (more by chance). We live in Hampshire, nursery is in Berkshire. We are right on the Hampshire/Berkshire/Surrey border so it's a fairly local nursery, my daughter attends the primary school it's attached to.

We have been trying to access Inclusion Funding since the day he started nursery and over a year later we still have none and are in a horrible gap. We have tried talking to Hampshire and Berkshire local authorities with each saying the other is responsible for the provision. My sons therapists (Physio, OT, Teacher of the Deaf, portage) are Hampshire based and cannot really go into the school to support as it's in a different county. We cannot access the Berkshire versions of these in school as we don't live in Berkshire. Can you see where i'm going with this?!

We requested an EHC assessment from Hampshire due to the lack of any support we are receiving and this has been declined on the basis that he is well known to Hampshire Children's Services and they feel his therapies are adequate for his needs and we adopt a wait and see approach. Well, this wait and see approach is meaning he cannot proceed in his development! We are waiting on mediation although Hampshire SENDIAS have said to cancel this and go straight to tribunal given our background.

I feel we are getting more confusion the more we investigate. Hampshire told us that there was definitely a reciprocal agreement in place with Berkshire to access Inclusion Funding, yet Berkshire deny this.

I have called Hampshire Social Services twice to beg for a disability social worker to support us in this (as well as some other things) and to call a Team Around The Child Meeting as i feel getting everybody in the room together would be the best thing. However despite me, as a parent, sobbing and begging for support i was told we don't fit the criteria (my son is considered 'age appropriate' and must have a lifelong disability - er, he has Down Syndrome?!) and to Google parent support in our area. Considering a formal complaint to them but mentally i've had to take a break.

I want my son to progress in nursery, to be able to move in the nursery with his peers, which is what is recommended for children with Down Syndrome (and i have this documented from a professional). However without the funding, we can't do this and I am fearful that the nursery, as amazing as they are, will not be able to support his needs.

Any advice on where to progress from here?!