I used to tour in a band from 1999 - 2008 with my European booking agent based out of Bristol UK and spent alot of time in both Bristol and South London, Putney/Battersea and I have had quite good gear over there. I know suboxone is popular in UK along with certain cases there being Diamorphine clinics similar to methadone clinics but using pure Heroin as "treatment" may be something to look into if that is your d.o.c.