If your wedding is taking place overseas or you are planning an exotic honeymoon, it is worth considering wedding travel insurance.
Depending on where you are travelling to and why you are travelling [i.e. for the wedding itself or for the honeymoon], there are different companies who will be able to assist you.
Many of the main insurance brokers also specialise in wedding travel insurance as well as some of the large department stores. It may even be worth asking your travel agent if their policy also covers your wedding.
Remember that most insurance is a minimal cost in comparison to your overall wedding costs and although no-one anticipates problems, it just insures you are covered if things do go wrong.