Tapatalk (which is an app for iphone, ipad, andriod etc) have a plugin for vbulletin (the type of forum this is) - worth talking to the forum admins to get them to install it. Tapatalk has its draw backs, but its pretty good.
An app is a good option, but please, please, no warning that there is such an app when you access the forums from a mobile device's browser. Those constant nags make some sites unusuable. User choice is everything.
Go to the forum page on your iThing in Safari.
Tap on the icon that is an open topped box with an arrow pointing up.
Choose the option "Add to home screen"
You will then have an icon to tap that takes you straight to the mobile version of the forum..... like an app, but not an app!