If you're using a family computer, the site may have been blocked by a parental control. Before attempting to bypass the site, ask a guardian or parent about using the FH forum to not cause trouble or hassle.
The issue may also be being caused by your ISP's settings, as Virgin Media is a service provider for the UK.
If not and you are using a personal device, do you have a web filter enabled? If you don't have an account for the software blocking the site to allow connections to the FH login page, contact your ISP or the filter provider about the issue. It may be being blocked because of some popups that the login page has had.
A moderator would also be a good person to ask about potential site issues.
Hopefully you get this fixed soon!
Cheers!
~ Whisper