SEN-only or primarily for children with SEN private schools should be exempt. The only controversial part there is that they need to exist at all, and that most of the parents have to pay for it.
Some private schools can be awful for kids with SEN, though - I don't know where it's come from that private is automatically better for kids with SEN. The academic pressure and lack of vocational courses at GCSE and above can make some private schools a nightmare for kids who don't fit the academia-at-all-costs ethos of many private schools (obvs excluding the ones that are SEN-focused).
Who knows if it will make state schools better in the long run, but will it raise some money? Yes. Will it mean that schools that aren't really charities lose some of their fake status? Yes. Will it mean some parents actually consider local state schools that are actually good schools? Yes.
And no, it won't mean kids going back to state school next Monday instantly have a better education. Damn Labour for not making generational changes overnight!
I think that’s fair.
I think, however, I individually can’t make any difference by not sending my child to a private school. I (we) want the very best for her. Part of this is giving the best education possible. In London at the moment this means a private education.
There are an awful lot of really good schools in London. If you missed out due to overcrowding meaning your kid didn't get a school place, or your kid had SEN needs that weren't being catered for, that'd be different.
Also, a lot of parents in London who choose private school do it to avoid the brown people/Muslims/other undesirables. You're not one of them, but many of the other parents will be. It's one of the things that would put me off if I had tons of money and private school was an option.