@ItsAShame2 the legal advice you were given was completely and 100% incorrect.
I have friends who have kids in EHCP funded independent specialists, and state specialists - most, but not all, secured via appeals. My own daughter has an EHCP funded place in a small private mainstream, with classes of only 15 in a green calm setting - she has a 1:1 TA to help her, and OT and SLT as well as play therapy. My son has a complex EOTIS package (most people call it EOTAS, but judges hate that, so I am retraining myself to say EOTIS!).
Our LA is actively trying to place kids in small mainstream independents right now, because the (fantastic - if they weren't for MDL when my kids are able, I'd also be fighting to get them in) state specialists are already so full they're well over PAN. And small mainstream private is cheaper than specialist, state or private alike, so they are really pretty open to that as a path here. It costs less. It can even cost less than mainstream state in some cases, just because they may not need a lot of provisions implemented for that one child, as they're part of the standard offer.
If you want to PM me, I can talk you through the process. If you are unable to access mainstream provision without distress and harm due to unmet need, then an EHCP can and must provide for an education that child can access.
An EHCP only takes years if the parents don't know the legal mechanisms to ensure otherwise, too. Knowledge is absolutely power here. It's slow, but can be forced into a year or 18 months or so if the right steps are taken. And apart from anything else, the assessment reports are so, so valuable in knowing why and how your child struggles, and what needs to happen to help them.