I would suggest that a good quality service is about how the service is provided as much as it is about what the service provides. For example, there is a considerable amount of evidence that in counseling ('talking treatments'), outcomes depend more on the nature of the relationship between the therapist and the person than on the specific intervention or treatment modality used by the therapist.
Drug & Alcohol Findings is an excellent site which collates research into various subject areas- I recommend checking it out.
Here's a link to one of their articles which may be relevant to your question;
Paul, that an excellent summary. I'm very grateful. I'm also in the middle of an assignments on dual diagnosis, mental health and and a tough case study on how to deal with a client presenting with self harm after a long history of alcohol and benzodiazepines and a family history of suicide. Any tips would be welcome. Kind regards, Liam