Hi Julian,
Welcom to Visual WebGui
In general it is much easier to use .ASHX rather than the default .WGX
There is an excellent article by Palli which shows how
http://www.visualwebgui.com/Developers/Resources/Tutorials/tabid/365/articleType/ArticleView/articleId/548/Deployment-of-DHTML-Visual-WebGui-application-with-different-extension-than-the-standard-WGX.aspx
I am not clear how your virtual directory is set up as http://www.midnorfolknews.co.uk seems to point to the same IP as 2 other web sites that work.
What you should try is creating a simple ASPX web page, deploy it to your web server and check that works.
If you need more info on Virtual Directories in IIS see
http://www.startvbdotnet.com/aspsite/extras/virtualdirectory.aspx
In the Virtual Directory you must have a web.config and the bin directory with the correct permissions set.
Make sure you have set Copy Local to True for the Gizmox DLL's on your development PC and then you can FTP the directory to the web server.
Please make sure you increment the PrivateVersion each time to make any changes to web.config
I hope this helps
Jay