N.A. is a non-profit organisation for people who have problems with substance abuse.
The primary service provided by Narcotics Anonymous is the local meetings (held weekly). Each group is autonomous, organising itself according to a series of 12 principles common to the entire organisation. Some groups may be 'open to all', meaning anyone can attend or 'open to addicts only', meaning only for people who want to address their own drug problems. Meetings are facilitated by NA members.
There are local groups in Earls Court, Notting Hill, Chelsea, Ladbrooke Grove among others. See website for details.