I want my landing page on Moodle to show my course categories when students type in the URL - it is only showing the individual courses - Ideally what I want to be able to do is set up 10 course categories (for different departments) and then once these are clicked then to release the full set of courses available under this - is this possible. Cheers I'm new to the admin side of Moodle so all help much appreciated!!
What you're describing is one of the key features of the Moodle front page. Appearance will depend on the theme you're using.
The exact options can be found in paragraph 4 of the docs page.