It is not only illegal drugs that can be problematic. Caffeine Coffee is consumed by the gallon by many students. Caffeine is recognized to have side effects that are not widely known. Tobacco Smoking is still quite prevalent in the UK especially amongst young people.
Cigarettes are more expensive in the UK than in many other countries due to high taxation.
In the UK it is currently illegal to sell tobacco products to children under 16, although the use of tobacco products by children under 16 is not in itself illegal. However, when 'drugs' are discussed it usually refers to illegal drugs. You need to know the law in the UK as drug offences can be dealt with very harshly. Drugs and the Criminal Law Drugs laws in the UK are inconsistent, with some quite harmful substances freely available, and others prohibited. The majority of offences are related to cannabis.