I'm also perplexed as to why the private school education is relevant, tbh.
But anyway: you say your son wants to learn but doesn't want to go to university - does that also preclude other kinds of college learning? It sounds like he might enjoy an apprenticeship, which involve real work combined with study modules (day release to a local college or whatever). I have a young relative who is doing one in electrical engineering; I don't know if they do business training ones, but you could google 'apprenticeships' and see what you get.
Alternatively, he could research the big banks/companies etc and see if any of them offer entry schemes at your son's level. I vaguely know one guy who is now a senior partner in one of the big banks, who didn't go to university (and is now earning squillions of quids). He started at the bottom and kept going up with impressive drive and ambition.
Which I suppose raises the question: does your son have impressive drive and ambition? Because if he's going to build a business career without university, he will need it. If he doesn't, he may need to get more realistic.
A third option would be an unpaid internship - again, he needs to research themarket and make approachesto the right companies. They will not be impressed if you do this on his behalf!
And I suppose a fourth option is to research local businesses and see if he can get a job with one of them, then negotiate some paid study leave to do a course at the local college or through the Open University.