Aha! Sorry, Penstemmon, but I've come cross so many advisors who really don't understand the practicalities of the situation. They want SEND children to have extra support, but don't seem to realise the pressure that teachers are under. I left teaching before performance related pay became a big deal, but the pressure was bad enough even then. Teachers are working 60+ hours a week and are becoming paranoid if they don't reach their targets. They are very likely to be sacked, especially if they work in an academy.
With all due respect, allowing a child to wear pyjamas is almost guaranteed to single a child out and lead to teasing or bullying. I worked in a special school for a while, where a number of the pupils had sensory issues. They wore soft cotton underwear (even in Summer) and a couple wore gloves.
A quiet room is fine and many schools have them, but it needs to be staffed, as do small groups and extra pastoral staff to be on hand when needed. There is no incentive for schools to fund them, especially if the school is struggling to meet its targets. That's the reality.
The really important thing is what happens in the classroom. Advisors have sometimes suggested a different way of working to satisfy the needs of a SEND pupil. However, this means changing everything for all the other pupils as well. An advisor once told me that an autistic child couldn't concentrate with posters on the wall and other pupils talking. She suggested that pupils should work in silence for most of the lesson. I'm sure this would have aided the SEND pupil's concentration, but unfortunately, I was a languages teacher and I WANTED the pupils to talk to each other in pairs or groups for much of the time.
Schools which put extra resources into SEND risk alienating the parents of pupils who will achieve high grades to impress other parents and place the school high in the league tables. There is a school just like that near where I live. Being in the catchment area of that school depresses house prices and parents who can afford the fees send their children to private schools. That particular school has an excellent reputation for SEND, but it's become a failing 'sink' school. The situation has become so bad that the school has now created a high-achieving stream to tempt some parents back.