You should register with an NHS doctor (known as a GP) for everyday health issues.
You can use the NHS for free, including NHS hospitals. You may be asked to show the stamp in your passport or BRP. You do not have to pay the immigration health surcharge.
Find out how to register with a GP in Northern Ireland:
ENG:
https://www.nidirect.gov.uk/articles/your-local-doctor-gp
UKR: