i've read where there are pharmacy's that don't carry it. You can get it before hand but will have to find a place that will fill the script.
What good is it if you go fuck up on a Sat night and your doc's office is closed? I guess that's why they do it in advance. Depending on where she lives, she may have a hard time finding someone to fill her script.
They are working hard to get it over the counter in the US. England has lead the way on this one, however the fda is really dragging there feet for political reasons only. All the scientific evidence has proved its safety, even amoung girls 16-18. One of the benefits of the push is if it is on the self than a male would be able to buy it for his partner, currently here this isn't an option Dial_tone.