If you are being presented with the Access Denied screen this suggests you are not taking the correct route. Try the following:
If you are logged in then log out
Clear your Browser History and remove any bookmarks for this site. Close down browser.
Reopen browser and go to www.forest-of-dean.net
Click on Forum and then Login.
Complete login process and you should be able to access the various databases.

If problem persists then raise a ticket:
http://www.forest-of-dean.net/joomla/index.php/help-faq/help-support-contact-form

Mike