The Cocktail Bar can also be acquired from card pieces, which you can receive from your free daily booster packs, or cards from visiting friends. Of course, you can also trade other players for Cocktail Bar pieces.
If you don't get the Cocktail Bar right away, don't worry. The story quests are not required to progress in the game, and you will keep getting other story quests when you level up, even if you haven't completed all of the previous ones. Guest wishes also change after a while, so you don't need to be worried about guests with unfulfillable wishes.