I agree you should escalate this. Cabin crew should NOT sell alcohol to anyone who is abusive, this will only cause more trouble. If as a passenger you felt unsafe because of what happened then you should definitely complain to the airline and the CAA. You didn't say if you had any witnesses.
The trouble now is the problem of 'soft justice' in the UK court system. Drunken passengers are a regular feature of the newpapers and get away with it to fight another day. Here is another bad example:
Former air stewardess flying to London for honeymoon kicked cabin crew and shouted: 'F*** off. I'm going to shoot you in the face' | Mail Online
I posted this in Jet Blast for interest.