As Colin mentioned, you can't restrict the Front page to enrolled users because you can't really enroll anyone there. But I think you are on the right track with your original idea of changing the navigation.
Try setting Appearance > Navigation > Default home page, to My home. This will accomplish the redirection from Front page to the user home page for everyone, where the Course overview block will take them to their courses. (By default: check Appearance > Default my home page.) Also, uncheck the Show front page activities in navigation box on that screen too.
Next, as you are thinking, you can then hide the Navigation block's Site home link in CSS, or you could also hack it so that the URL parameter "?redirect=0" is taken off, since any use of the bare site url (moodle.domain.com etc.) will redirect users to their My home page. There may be some other loose navigation ends to shore up, but the My home does the heavy lifting of redirecting the site to the user home page.
A useful thing to know is that adding that no redirect=0 parameter will bypass this forced redirect to My home, which is a trick you can use as an admin to still reach the Frontpage if you need to for some reason just by adding it in the browser address bar.
(Incidentally, as you are on
2.7, know that in 2.9 the My home page is built out more as a user
Dashboard, and there will be more future work along these lines.)
Not a %100 solution but about %98 with much less effort than custom coding.
If you actually need different landing pages based on cohort membership, that's going to take some more complex coding, but the idea would be the same: redirect the Frontpage or even My home to a course used as a landing pad based on cohort membership.
Randy
