Mrs messenger

Going on Anthem of the seas next year from Southampton. This is our 1st cruise. Family of 4 which includes 21 year old and 18 year old. We never purchased drinks package at time of booking as travel agent told us to look out for buy one get one free deals. When a deal came up it was for new bookings only so she gave us wrong information. My question is this, we are away for 8 days, the deluxe drinks package works out at £50 per person per day =£1600.00. Are the drink prices onboard very expensive as just wondering if we would be cheaper just paying individually for drinks as we go as we will be off ship most days visiting the ports. Any advice would be appreciated.