I have never shot a wedding, but have shot people in changing light. Obviously there will be outside shots, a slower film then 400 may be indicated.
If you use two film speeds, use the same line. It is not attractive to me, to have photos in a series that change character. Like Plus-X is to Tri-X, a good match in the color, grain and contrast would be desirable. My choice would be Portra 160NC and 400NC. And I would also add a b+w for some classical looking images.
Lastly, whatever film you choose, practice with a few rolls first to get to know it and the results you want, IMHO.