If you need a PCR test for travelling abroad you can find them on this page: https://www.mayfieldclinic.co.uk/covid-19/departure-packages
If you need a PCR test for arriving into the UK you can find the right test for you here: https://www.mayfieldclinic.co.uk/covid-19/arrivals-testing
If you need a PCR for general purposes you can access either same day or next day services.
Same Day PCR: https://www.mayfieldclinic.co.uk/covid-19/same-day-pcr-test
Next Day PCR: https://www.mayfieldclinic.co.uk/covid-19/next-day-pcr-test