Have the tories explained how they are going to fund and manage National Service? No, they're going to establish a Royal Commission to look into it.
I don't think VAT is the right way to do this.
I think it's fine to have policies which are ideological. Changes to inheritance tax is also ideological. I'm opposed to provate schools - I think they are bad for society. It's normal to use taxation to try to change behaviour. You make it harder for people to do things you think are bad for society, like gambling and drinking and buying full-sugar coke. I wouldn't use VAT though - it doesn't feel right.
I feel sympathetic for the children who will be affected by this, and their parents - especially those with SEN children (have SEN children who can't attend mainstream, I can't afford private, I feel very sorry for anyone who found a sokution and may lose it - additionally, SEN children are likely yo make it harder to work, so parents of SEN children are less likely to be able to find additional funds).
But all policy changes have unequal impacts and you can only mitigate them for a certain amount of time or to a certain degree. Changes to thresholds for benefits affect people, changes to stamp duty thresholds etc.
It could be mitigated - you could allow anyone with children already in private schools to claim the tax back one way or another, or for a limited period of time. It would be really easy to do it through the school's VAT return.
But the level of hysteria and focus on here around VAT on private school fees is really quite weird. (I have a professional interest in VAT - I realises that's why I keep reading them!).