This article in Magistrate magazine suggests that community sentences are likely to be just as good as custodial sentences at reducing reoffending and drug use and, given the high costs of prison, they are likely to offer better value for money.
It draws on the findings of the report Reducing Drug Use, Reducing Reoffending. This considered whether interventions within the criminal justice system (CJS) aimed at problem drug users are effective at reducing drug use and offending, and whether they offer value for money.