School vouchers are an idea that has very limited popularity outside the American right. I think there are two ways you could implement a voucher education system, of which I think one would be a terrible idea but the other might well not be.
Model 1: The government says “if you like, rather than giving you a free place at a school costing £x a year, we will subsidise you for £x a year to have your child privately educated at an institution of your choice. If you choose a school charging £y<x they’ll be educated for free; if not, you’ll pay £(y-x)”.
Model 2: The government says “if you like, rather than giving you a free place at a school costing £x a year, we will subsidise you for £x a year to have your child privately educated at any institution of your choice that does not demand additional fees; if you want them to recieve an education costing £x+1 then you’ll have to pay the full £x+1 yourself”.
I think that model 1 is a really bad idea, because a) it will result in a higher fraction of education spending going to children of rich parents who can afford to pay £(y-x) and b) it will result in all the existing private schools realising that they can now charge an extra £x for their services and all their existing clients will still be able to afford it.
But I think that there’s a lot to be said for model 2. Things like zero-tolerance schools are a) incredibly controversial and b) often produce good results. Yes, they sound grim, and if I thought my child had a good chance of a decent life if I sent them to another school I’d do that in preference, but if I didn’t – if I were a poorly-educated parent from a deprived area where the local state schools were awful (as they often are in deprived area) I would probably pick zero-tolerance. And I think that that kind of alternative educational model – and lots of others like it – will flourish better in a system where some education is subcontracted rather than provided directly.