It depends on what you actually want from private education.
If you want a "better education", ie. for your DCs to finish school with better exam results and to be engaged, interested students - then no. Typically you are not going to get good value for money. There are loads of excellent state schools filled with talented teachers and hardworking pupils. And tbh, your home and family life will generally be a much stronger support structure for your DCs academic success than any school.
They're also not good value in the sense that if you set aside the money you would spend on fees, and spent it on private tutors and language lessons, sports coaching and educational trips to supplement state school education, you'd get much more value for money - and highly personalised education.
But what a private school can and does buy children is a peer group who (pretty much) all come from an affluent background, who they will likely remain friends with through university and their careers, and can rely on for networking opportunities and 'hidden' jobs. They also instill a sense of privilege and superiority in children, which can give them a kind of confidence in their young adult lives. if you think that these are positive things, and that education and job opportunities should work along these lines, and that this is a good message to instill in your children then yes, private school would probably be worth it for you.