Most commercial wedding venues such as hotels will be very happy to supply you with champagne - you can normally opt to supply your own but the corkage charges don't usually make this advantageous. If you are having your reception at a private house your option is to buy from a wine merchant or the supermarkets. Even with the best deals, serving champagne to many guests can be expensive. Here is an idea to cut down on the cost and have an enjoyable mini break.
UK duty is £2.63 per bottle of champagne which all commercial companies have to pay. However if you visit France by car and drive back with champagne for personal use then no duty is payable. So if you bought 100 bottles back you will have immediately saved £263.
You could just take the ferry or tunnel over for the day and shop in Calais. This way you cut down on travel costs and you should be able to do a deal with one of the many shops in Calais before you book your trip.
Even more enjoyable would be to drive down to the Champagne region (about a three hour drive from Calais) and visit some small producers before deciding on which champagne to buy. Most of the 300 or so champagne villages will have several small producers who will be open for tastings. My suggestion would be to base yourself in or near Epernay. Make sure you visit the Avenue de Champagne and one of the big champagne houses such as Moët & Chandon while in Epernay. You could do a little research beforehand and make sure you have a few producers names who will be open for tastings.
Once you have paid for accomodation and the travel costs you probably won't have saved that much. However you will have had a pleasant break, visited Champagne and have your personally selected champagne for your special day.
If you need any more help or advice for a trip over to buy champagne please contact us at Just Champagne.