kev111
All I can say is that:
1) on my Android phone and on my Windows laptop I use this link to sign into My Virgin Media Account.
https://www.virginmedia.com/my-virgin-media
That takes me to the page you have posted. When I press "Sign in" it takes me to the page where I enter my VM email account user name / or VM email address.
Or if I want to sign straight into my VM webmail account I use this link
https://mail2.virginmedia.com
That takes me to the page where I can enter my email address.
2) If those are not working for you I would suggest switching to using Safari's Private Mode. See here for details of that:
https://www.electronicshub.org/go-incognito-in-safari-on-iphone-ipad-mac/
If it works in Private Mode that suggests there is a corrupt VM cookie in your Safari browser and deleting VM cookies from the browser usually cures the problem and you can go back to using Safari as normal.
Coenoby