@julian Thanks, I'm aware of suggested topics, we're already using that but it gets topics from other categories too. Which doesn't work when you just want to focus on certain type of topics (a category) only.
User groups in categories permissions
In the access control in the admin area you have "read" & "write" against the groups, when I click on the read & write options they go grey but do not appear to change my ability to read or write to that particular category, is this purely because I am a admin or am I missing the point?
Yep, as an admin, you automatically have global access to all categories.
You can create a new unprivileged user to see how it interacts with regular users.
@julian thank you will have a play, but is the access default read & write on? as in white and too restrict grey?
No, the default is "off", but keep in mind that if a category has NO restrictions at all, then it is globally accessible.