Livre d'Or

In the UK, Jewish communities have the right to perform civil marriages. But in order to do that they have to be an actual community, they have to have a board and a formal, quorate meeting where they vote to appoint the person who fills in the paperwork for the registry office. That means that random little groups of friends who decided that mainstream communities were too boring generally can't perform civilly valid marriages. But yeah, they could do the registry office the day before thing, and there is no absolute religious requirement for a rabbi to be present (a marriage exists between the two individuals in Judaism, it's not a sacrament).