It is a crime in the uk to be drunk on a plane
Yes, it is a breach of the Air Navigation Order, a statutory instrument.
Drunkenness in aircraft
75. —(1) A person shall not enter any aircraft when drunk, or be drunk in any aircraft.
(2) A person shall not, when acting as a member of the crew of any aircraft or being carried in any aircraft for the purpose of so acting, be under the influence of drink or a drug to such an extent as to impair his capacity so to act.