I remember reading the law and case law on this a while ago, basically a wedding car can only be classed and used as such on the day of the wedding only, not taking "the girls" on a hen night the night before or the day after the wedding unless the car is taking guests home or to places after the ceremony and celebrations. Anything else is not allowed.
Contrary to some beliefs, the "wedding car" exemption does not apply to buses or large "novelty vehicles" from what I recall.
One bonus is that cars used in connection with a wedding or funeral are usually exempt from parking regulations!
