I wouldn't use the app - it turns out that it can now invalidate insurance, as per my banks recent mail.
https://www.nationwide.co.uk/-/media/MainSite/documents/products/current-accounts/flexaccount/P3938-flexaccount-travel-insurance-summary-of-changes.pdf
"You’re cancelling your trip because either you, a travelling companion or the person
you’re planning to stay with during your trip has been advised to quarantine/self isolate (either abroad or in the UK), and it’s not for medical reasons. For example, if you’re contacted by NHS Test and Trace but don’t have symptoms of or haven’t been diagnosed with Covid-19."
Nice. Therefore, don't feed into the system. If you feel unwell, isolate and maybe get tested.
Biting the hand that feeds IT
