What will it take to be prescribed a benzodiazepine?

i understand how dangerous it is and that their is alternatives to treat my disorder(social phobia). But ive tried three anti-depressants already and dont have much hope that any of these other meds are going to work. If i were to take the lowest possible dose every friday and saturday would i become addicted? Also i use marijuana and already told my doctor, so hes telling me that if i used benzos temptations would arise to use marijuana.