I think a good idea is each time you are buying a bottle for home select a different one and use that as your selection process to what you would like for your wedding. try 1-2 bottles a week and when you find what you like then start worrying about costs and discounts. Remember that for a wedding you want a wine that will appeal to many, not just yourself. Chablis is a great choice (bought that myself) as its an easy drinking wine, be careful with the red, you dont want to over power the meal with a big heavy wine. So again go for a softer milder wine, Fleurie / Merlot are ok but its all down to taste. Enjoy the selection process then do the deal!!