Hi DD.
I do a lot of this for myself so happy to play a little
It's best if you try to associate to the different aspects of your dream yourself, including the emotional content. If I understand correctly, you did not drink in your dream after all, right? How did you feel when you woke up from it, disturbed or satisfied?
One thing you can try is to imagine that every character in your dream represents you, aspects (projections) of yourself. What do they mean/symbolize to you this way? The one that you identified in first person as "yourself" within the dream? The Billy Connolly figure? Your father and mother? Try to think about stuff (events, context, emotions, any kind of association) that comes up from your mind quickly when you think about them. Can do the same with your dream environment and imagery.
Here is what I came up with very quickly after reading it, but it's my associations so don't take for granted. Quite simple, actually. Let's assume that we take Billy Connolly as a positive, attractive figure.
It's a temptation to drink. You know you should not (have a "class" and "work", means another business to do), but the temptation is too strong so you skip it. Then you start to chase your urge and the alcohol. Billy Connolly represents the craving and the "positive" aspect of drinking that attracts you (advertises it even). The top floor with no roof and open night sky is perhaps that you want "out", want to be "free" to drink, without risk.
Then suddenly you are "inside" again, constrained...the temptation morphs into your conscience and inhibition, represented by your parents. But you are pissed, because part of you would still want to drink. But "dad" is still there... then probably due to the strong emotional content, you wake up.
Try your version of associations.
In any case, you survived the dream craving unscratched, didn't you?