I am neither religious nor royalist, so have no axe to grind at all about whether King Charles should be head of the Church. I dare say that's up to the Archbishop of Canterbury, but I wouldn't argue either way.
I have mixed feelings about whether there should be a complete separation. Part of me thinks that religion should be a purely individual (or family) matter, and no particular one should be given precedence, but OTOH, British culture has long been based on the Christian religion, with Christmas and Easter holidays being the main expression of that. I think that having Bank Holidays that most people can observe at the same time is a good thing. I sympathise with those from other religions who don't have their holy days honoured, but as often as not companies can do a trade and ensure that employees willing to work Christmas can have Diwali or Eid off instead. I hated Sundays as a child (I had to go to Sunday School and wasn't allowed to play outside), but can't help wishing that we all had a family day now - not for religious reasons, but a day when mum and dad are both at home and the family can all sit down in front of a film or fall out over a compulsory game of Monopoly
. Or maybe not
.
Not great in unhappy families, I know, and it wouldn't work for everyone, but I think it's a shame that family life has to come second a lot of the time.
I very much think that comparative religion should be a core curriculum subject, to encourage understanding and promote tolerance. I wouldn't keep Christian assemblies, but I don't think I would go as far as to ban all religious symbols in schools as I believe they do in France.
It's tricky, as whatever any of us think, people will believe what they believe, and attempts to ban them from doing so have never ended well.