How do pharmacies work with non residents?

Hi there. My partner and I are traveling here in the Uk and we are set to leave in about 30 hours.

Unfortunately my partner got sick and vomited up her dinner. So it might have been food poisoning and/or some travelers sickness.

She is doing better now that she has a full night of rest but is still pretty nauseous. Can we just go to the pharmacy and ask for anti nausea medication ? And if so, how much would it cost roughly?