> The majority of state school provision in the UK is atrocious.
I don't think this is really true anymore. I agree state schools were truly awful in the 80s/90s (my partner who went to state school didn't even learn times tables). Quality of state school has improved tremendously over the last 20 years, and I'd say it's very good these days. Especially as middle class families are priced out of independent schools. In fact I'd even say it may be better for your kids to go to the local state school nowadays, otherwise you are isolating them from their local community.
> Not a penny of your tax goes to subsidising their education.
I, of course, totally disagree :). I toured many London independent schools last year for secondary, and you just need to take a look at the amazing school grounds to see the benefits of charitable status. [1] These are for-profit institutions with huge bursaries that avoid paying almost all taxes. Any tax exemption is equivalent to a subsidy that I am funding as a taxpayer.
1. https://www.gov.uk/government/publications/charities-detaile...