Driving instructors using illegal drugs

There's a code of conduct for driving instructors, however it may be a difficult task to prove your allegations. Although I understand your concerns, I must say that unless the driving instructor was unfit to teach a learner through the use of illegal drugs and the learner reported him to the police when that happened, it would be really difficult to frame him.

You can try reporting him to the local police or contact the Driving Standards Agency (DSA) to make an official complaint though.

If he smokes and then drives while intoxicated then this is clearly illegal and he could lose his driving licence and his job (as he would be putting people's lives at risk).

Although smoking outside of work is of course still illegal it is not likely to impact safety and certainly does not sound as though it affects his job. Similarly if someone drank every night, although this would not be good for them (or perhaps those around them) it would not prevent them from doing their job.