This is my intuition talking but your post screams heroin addiction to me. In the case of addiction it is my experience (personal and from many many others) that a person has to want to get help and has to admit they have a problem. I think it is similar with mental illness. If you force someone into the hospital and they are given meds or are forced to be clean for awhile the chances are very high that they will just return to their life style. Some people go to rehab multiple times to get people off their back or to satisfy the court and relapse over and over.

On the other hand. In the US there is a thing called drug court. This started when they got very serious about drunk driving due to the lobbying effort of Mothers Against Drunk Drivers. So if a person gets two or three drunk drivings they are forced to attend a certain number of Alcoholics Anonymous meetings. As a member I have never really agreed with this as it violate our traditions. It was supposed to be people who voluntarily choose to join. But I have to say I have seen many many people who are forced to go and somewhere along the line decide to stay and have lasting sobriety. Drug courts have proven effective overall. It keeps non violent drug offenders out of jail and often works. But this is a matter of someone already caught up in the criminal justice system and they are given a choice. Do this treatment plan or go to jail. If it doesn't work they end up in jail and keep repeating.

In Alanon we say "You have to let an addict suffer the natural consequences of their actions." This is really hard to stand by and watch. It can be said of anyone. They have to suffer the natural consequences of their actions no matter the cause.

Chances are that she will get caught up in the criminal justice system in a more serious way at some point. I am not sure how it is handled in the UK.