The customer authorization (provided in the link you clicked) is out of date, and does not entitle you to use the Blended Threat service.
https://www.gov.uk/guidance/living-in-europe?utm_source=1a08afcc-a1a5-416a-94f1-2250f450ca8f&utm_medium=email&utm_campaign=govuk-notifications&utm_content=daily