I don't know if you will find a walk in doctor who will do this, perhaps if you are up front and honest they might, but my family doctor gives me a prescription with 3 'repeats' on it when I go and see her (routine meds, low risk, no need to see her more than once a year if that). Which means 1 doctor's visit, 4 x 3 month prescriptions (they are kept electronically online at the pharmacy for me). I don't believe there is a need to use them within a year (I say this because last time I got a repeat at the pharmacy she asked me if it was a repeat for a different drug I haven't taken in a couple of years). Just another thought.