Well...
I thought I'd try logging in to my webmail - and blow me down it worked!
Both routes - login to My Virgin Media and then on to Email - and direct via mail.virginmedia.com worked OK.
I'll give it a couple of days before declaring victory, but what a relief after 6 weeks of 'mailbox unavailable'!
Thanks to all the VM folks who've had a hand in getting this sorted, both on the 150 phone line and here on the Forum.
joe