Did you know that dentist's can prescribe medications? Not just antibiotics or painkillers associated with teeth problems but basically anything. I'm guessing the UK is same as USA because a dentist is a doctor by title and study.

In practice a dentist won't give you a prescription if you just walk in offs the street but if yous a regular patient of his and say lose your prescription or your doc is closed, you can ask him. I done that a few times, basically because the dentist is real close and the doc a long hike.