Most cases of nausea and vomiting do not require antiemetic drugs, but when they are needed, what are the choices?
www.nps.org.au
These are a few of the medical conditions that require antiemetics.
You can choose one and research its symptoms. There are guidelines available or you could go through people's experiences around it to better understand the illness and be ready for questions. Migraine would be my pick.
I am not sure how you can get it without a prescription in the UK but if you decide to talk to GP make sure to mention your preferred drug as it worked well for you in the past.