"I'm not just talking about private school, it is 1 example however now you've raised it: if you live in an area with poor state schools (yes these areas do exist) and you want something more for your child then you are called posh/elite etc for choosing to pay for your child's education and on here accusations of being "a posh Tory twat" amongst other things"
Virtually every parent wants more for their child when living in an area with poor state schools. Some will be able to find ways to pay for private school, others won't. I think it's wrong to understand it as those who don't are happy with their lot.
Name calling relating to those who send their children to private school is a moot point if you don't understand their motivation for doing so.
As state education is available to all, private education is a luxury item. It may not feel like that when the state options genuinely aren't good. However, they will nearly always look less good (class sizes, facilities etc.).
Private school could sell off land and amend their offer accordingly and increase class sizes, allowing the cost of VAT to be absorbed. Introducing VAT could sporn a different type of private school, build around cost per pupil funding aligned with state school per pupil funding. This would provide a more affordable option. All they need to do is ensure the quality of teaching and learning is better as class sizes and facilities would be comparable!