Many LDS members aspire to be married in the temple. However, it is an interesting fact that not all countries recognise an LDS temple marriage as being legally valid. This is the situation in Argentina, Brazil, and Britain, for example. In Argentina, all marriages are performed at the local municipality by a registrar who is duly authorized to perform marriages. Then the couple may go to have a religious ceremony performed. In Brazil, all marriages must be performed in the state in which the couple resides. Since not all Brazillian states have a temple within their boundaries, the couple may then have their sealing performed at the nearest temple upon completion of the civil marriage. In Britain law requires that a marriage must be performed at a public ceremony. Since attendance at a temple sealing is restricted, a couple will be married locally by a person who is duly authorised to perform marriages. This person will usually be a registrar of marriages. The marriage can be performed at the local registrars office, or sometimes in an LDS chapel. Some Bishops or Branch Presidents have been officially given the title of a deputy registrar, so are legally able to perform a civil ceremony in the chapel. The couple will then travel to the nearest LDS temple (London or Preston) for their temple marriage. http://en.wikipedia.org/wiki/Eternal_Marriage

Yes. But they are not recognised as being valid. There is nothing illegal about a temple wedding int he UK. However, if someone gets married in the temple and no by a civic authority, it is not recognised as a marriage. It would be considered the sames as a common law partnership.