NHS test and trace have contacted me by phone/email because a close friend has tested positive. I have been to the site to fill in all my details - it says I don't need to isolate (because I am double jabbed) but it then takes me to a page where it says I should book a PCR test. Can I just check this is a 'should' rather than a 'legally have to'... it is very unclear in its wording, I suspect intentionally. Thanks.