UK people, what do I need to say to the Dr in order to get some cool drugs?

I'm trying to give booze a break for a while so I'm hoping to get stuff from the Dr. Nothing heavy, just like tranquillisers and stuff but Drs are so stingy sometimes so I'm going to have to say I've got some ailment.

What easy to fake medical condition should I pretend I've got just so I can get some?