I don't think P & O do drinks packages in the way you mean. ... Neil.
We are going on Ventura in a few weeks and I checked our Pre Cruise Brochure Which explains everything we need to know and there is no mention about a drinks package apart from celebarion packages which include chocolates, champaigne, flowers etc. Certainly not a package that includes spirits beers or wines.
We are going on Ventura Nov 22nd and have enquired today about a drinks package. Unfortunately not was the reply.
Thanks for all your replies and have a great cruise Addy and Carnegie.