Virgin do allow inbound HTTP.
To get your ip:
www.abyssunderground.co.uk/ip
If you have a router (you say you don't) you would need to port forward.
Check your firewall is off, including the windows firewall.
The other thing that can crop up is modems not supporting something called loopback. This means you can't view your site using your own external IP. Get someone else to do it for you or use a proxy e.g
www.proxify.com