Some medications are available over the counter in the UK but require a prescription in Germany.

Some medications are available over the counter in Germany but require a prescription in the UK.

The only way to find out whether or not you can get your medication over the counter is to ask a pharmacist... and it would probably be a good idea to do that first thing in the morning because (as you probably know) lots of places close early on Saturdays.

If your medication is not available over the counter then I'm sure the pharmacist will be able to advise you on how to go about getting a prescription. Medication that requires a prescription ("verschreibungspflichtig") can't be sold without one, but I don't think you have anything to worry about, the pharmacist will be able to tell you what you need to do.