This is I believe Cunards current policy "Alcohol Policy
Alcohol (duty-free or otherwise) is available for purchase and will be delivered to your stateroom on the last day of your voyage. Alcohol purchased at any port of call including the port of embarkation may not be consumed on board. It will be collected at the gangway for safekeeping and delivered to your stateroom on the last day of your voyage, prior to disembarkation. You may bring one bottle per person of wine or champagne on board to celebrate sepcial occasions. If consumed in the dining rooms or alternative restaurants, each bottle will be subject to a USD15 corkage fee." So there is a limited option to take on board a bottle of wine or champagne but no more.