What absolute rubbish I'm reading. You do NOT get any allowance to buy alcohol or drugs. I have been on Incapacity benefit (now ESA) and have currently been on JSA for 6 months. I am an alcoholic (been dry for 13 months now) Someone said "they are drinking day and night" So, i take it you're standing around town 24/7 watching? JSA for a single man is £65 per week, If a young person lives at home with parents then I'm sure he can afford quite a few cans per week.
This theory that the DWP will fund your habit is ridiculous. OK rant over time for a cuppa!