You could use the "my home" dashboard as their homepage rather than the site homepage. I've not tried this option myself as I've heavily altered the site homepage for a more graphical front end.
But the My Home page can show the categories and courses that the student is enrolled onto.
The settings to change are at settings->site administration->appearance->navigation
The default setting is site as the home page but you can set it to My home or let the user select according to their own preference.
Hope this has been of some help.
I've had a look at the My Home dashboard page as an admin and the course overview block doesn't list categories, only courses that have content requiring attention. While the course categories block shows all the categories. I don't know how your course creators would react to this but you could use their profile page, that should list any courses that they are a part of; if they create them Moodle automatically enrolls them as a teacher. Then they could use the breadcrumb trail to get to the category page from in inside a course. Otherwise it might be something to suggest as a Moodle Tracker issue or an admin block that someone could create.
I've done some PHP programming myself and modified our Moodle code a bit but I don't think I could create anything on that sort of scale.
...unfortunately I will also not now get the chance to try as the school is scrapping Moodle with the new academic year, they consider it under utilized; while I'm facing redundancy.
I have the same problem, an i wonder if you could solve it ??