My children are very academically able with severe needs. I have a boy and a girl.
At the time our LA policy was to have 30 kids per class. If necessary, by mixing age groups. There was no possibility for small classes in state provision locally.
DC1 started reception and completed infant school. Junior School was in OFSTED special measures and the staff pretty much did the opposite of whatever the advisory teacher said and generally unpleasant. She loved her friends and hated change and wanted to stay. Y4 teacher even more of a horror. Lasted about two weeks. DC1 came out with a pros and cons list (one pro - they can use the drinking fountain) and I took her out. She was already on the waiting list for another school.
I started EHE and she hated it. I engaged tutors and she would put her head on the table and refuse to engage. I was mortified by her brattiness. She got used to the tutors and they tried to find her a place in their schools. This is how we ended up at a single sex private school. They had lots of children like her and she was there from Y4 - Y13.
HOWEVER after GCSEs she decided she wanted mixed state sixth form. I cannot fault the specialist Autism teacher from the LA and the receiving state school. They worked with her on one page profiles, visits and meeting the teachers, taking photos and making orientation books.
For the first four days, I had several calls from staff about how to manage her behaviour and distress. On the fourth day, she came out with a list of pros and cons about why she should go back to her old school. (I had forgotten until I saw it that she did the same in Y4). Luckily for her, her old school had her back. It turned out that they had plans in place to manage all the things that the other school had been phoning me about. She is the same everywhere - they were just better at supporting. She also has a small group of ND friends which she has kept.
DC 2 - enjoyed being at infants with his sister. Also managed Y3 at juniors (still in special measures) but attendance less than 50% by end of year. Verbalised++ that "wants to be normal and go to school". We found single form entry - so still 30 per class but actual school was smaller. He lasted about til Easter and then I withdrew him.
EHE from Y3 - Y6. His target was to be back in school for Y7. I felt a lot of pressure to "keep him up" with peers in school so he could slot back into Y7. Hated Y7 in local state school with local friends. Was back in EHE by Easter.
Very upset about it not working out.
Went to open day of very small private school which was not selective and offered extremely personalised provision. I cannot overstate this. He went there from partway through Y8 until Y11. He wanted to go to a bigger 6th Form in state school. Lasted 4 weeks. Complete burnout. Took the rest of the year off.
Went back to local college. Massive struggles but really his last chance. Has private tutors for all of his subjects so effectively EHE just goes to college for social experience and to "be normal" but really struggles with the environment. He is expected to get exceptional grades.
I don't know if that is helpful. One child settled into the right school and pretty much stayed there. The other struggles everywhere he goes.
For us the right school was night and day, but the child does not always know which side their bread is buttered!