Two things are certain in England.
1. You cannot guarantee that it won't rain on your wedding day, even in July or August!
2. If it does rain on your wedding day then your photographer can get photos that you otherwise would not have had.
This year I have been unlucky to have photographed weddings in both high winds and rain which is by no means a perfect scenario. However, as a photographer you take from it the best options available and take advantage of any opportunities, such as back lit rain photographs as per the below image from Naomi and Anthony's wedding.
I can honestly say that I have yet to photograph a rainy wedding which was in any way less of a special occasion. No matter what the weather a wedding is still a fun and happy place to be!