At a Catholic wedding in England a registrar will be present to register the wedding, after the couple have made their vows. If he or she drops dead before that has been done, they would still be married in the eyes of the Church, and presumably themselves, but if they wanted to make it legal, they'd have to pop round to the registrars.

If they had a big row before doing that and split up, they'd have no need to get a divorce. But they wouldn't be able to have a Catholic wedding to anyone else unless they were able to get this one annulled by the Church.

I think the same kind of thing would apply for all religions in Englad, apart from Angiicans, whose vicars can register marriages themselves.