I was prescribed Wellbutrin/bupropion for depression last summer (here in U.S.). I'm not a smoker, but I realize it's also prescribed for that. Since SSRIs made me feel worse (lethargic, apathetic, sleepy, irritable), it was the only one that could get me out of bed in the morning and help me to remain active. I got up to 300mg/day, but that was too much as it made my heart race and caused anxiety and insomnia. I tried to go off it completely, but then I felt terrible, couldn't get out of bed. So, I'm back to 150mg in the am and it definitely helps with energy, doesn't cause sexual side effects like SSRIs and also, I've lost quite a bit of weight without trying. Not really good as I'm less than 110 pounds now, but I was 135 and that's too much for my height. At least my weight has stabilized around 109-111. Not sure what that is in stone. I hope this helps, but I don't know the precription rules in the UK.