After finding this thread as the top result on Google when searching for “using Virgin Media WiFi Hotspots on a laptop”, I was trying this for ages on a Windows 10 PC and couldn’t get it to work, which surprised me as I got it working when I tried a year or so ago.
Turns out the information mentioned in this thread is slightly incorrect and no one picked up on it so I thought I should register and make this post to help others.
Basically, you need to use a FORWARD slash, not a backslash!
So it should be vmedwifi/*my email*
Just to be crystal clear, if your email address was email@example.com you would enter firstname.lastname@example.org as your user name and then use your normal Virgin Media account password.