These fact sheets provide some useful information on drugs and how they affect you.
Click through the below links to access the information.

Drugs and how they affect you
Alcohol
Amphetamines
Analgesics (painkillers)
Benzodiazepines (Benzos)
Caffeine
Cannabis
Cocaine
Ecstasy
GHB (Gammahydroxybutyrate) 
Hallucinogens
Heroin
Ice (Methamphetamine) 
Inhalants
Ketamine
Tobacco