As long as you're not changing your type of broadband service (for example, going from fibre-optic broadband to broadband that's delivered down your phone line, or vice versa), you can keep your Virgin Media email address.
If you're moving from one type of broadband to another, you may receive a new Virgin Media email address.
That's verbatim from the V-media website - Moving Home section, self service section. I don't think a link to it would help, as you have to log in.
Thinking about, there's no reason why you couldn't operate the email account via webmail - while you adopt spurlash's solution and migrate your primary account to a domain of your choosing.
SD