Do you have any problems with alcohol or drugs or do you want to quit smoking?
On following websites you will find information about this:

There is a lot of information available from the National Council on Alcohol and Drug Dependence (NCADD) https://www.ncadd.org/
The National Health Service can also offer support in these matters as well as many charities and local help groups.
The NHS can provide help for drug addiction. For information on getting help with drug addiction check www.nhs.uk/Livewell/drugs/Pages/Drugtreatment.aspx
For information about why alcohol is bad for you or for help giving up: www.nhs.uk/Livewell/alcohol/
For help and advice on quitting smoking: www.nhs.uk/LiveWell/Smoking or here https://www.nhs.uk/smokefree
For a particular focus on youth issues relating to drugs and alcohol go here: https://www.ncadd.org/about-addiction/underage-issues/alcohol-drugs-and-youth