Assuming that it was an NHS test (rather than a private one associated with travel), the following applies:
"PCR tests are mainly for people who have symptoms. They're sent to a lab to be checked.
Most people get their result the next day, but it may take up to 3 days.
You'll usually get a text or email with your result when it's ready. If you use the NHS COVID-19 app, you may also get your result in the app.
If you do not get your results by day 6, call 119 (free from mobiles and landlines).
Lines are open every day, 7am to 11pm. 119 provides support in 200 languages."
Source:
https://www.nhs.uk/conditions/coronavirus-covid-19/testing/test-results/how-you-get-your-test-result/