Have you contacted the LA? They are unlikely to do anything unless you keep on at them. You need to be proactive. DC whose parents can fight and navigate the system get the best support.
Other than the placement does the EHCP meet DC's needs? If it doesn't you need to request a reassessment of needs. If it does, request an early review. IPSEA have model letters you can use. If the LA do not agree the former has the right of appeal, the latter does not.
Is the provision in section F specific and quantified?
If you EHE the LA are likely to say you are making suitable arrangements to educate DC and therefore they are relieved of their duties.
EOTAS is possible, it is important to distinguish it from EHE. What it includes depends on what is specified and quantified in section F. It's unlikely the LA will agree if they believe there is a suitable school.
DS1 has a comprehensive EOTAS package including tutors and therapies, some are provided direct and some via DPs. It is exhausting orchestrating it and if there was a suitable school for him he would be going.
You have the right to request a personal budget, although the La don't have to agree and you have no right to appeal. If they believe there is a suitable school it is unlikely they will agree.
Are there any other suitable schools?
Separately to EHCPs, LAs have a statutory duty to provide education to CSA DC out of education for more than 15 days because of their health (including their MH). See the guidance here. If the LA won't you can threaten Judicial Review, which usually prods LAs into action. If it doesn't SOSSEN can help with a pre-action letter.
I second heading over the the SN boards. There are a few of us who receive DPs, and some knowledgeable, supportive posters.