I am not doing the OU course but I have found these two other courses on the on the internet and I thought they might be useful. Both are complete and free amazingly. All the materials are there, lecture notes, course notes, course work etc but of course you don't get marked, any certificate or any help.
The two courses are;Astronomy 161 at Ohio State University
Not only do you get all the materials but the lectures are available as a podcasthttp://www.astronomy.ohio-state.edu/~pogge/Ast161/
Lectures podcast at http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewPodcast?id=192740136
8.282J / 12.402J Introduction to Astronomy from MIThttp://ocw.mit.edu/OcwWeb/Physics/8-282JSpring-2006/CourseHome/index.htm
Currently I am following the Astronomy 161 course (I am just listening at the moment). It is very thorough although maybe a little laboured particularly if you already know some of the stuff. Note that the fist lecture is on metric measurement - don't let this put you off remember our American cousins still use the FPS system and haven't generally haven't a clue about metric
It soon picks up pace.
The main sections of Astronomy 161 are;Part I: The Starry Night
Unit 1: Introduction
Unit 2: Discovering Earth & SkyPart II: The Rise of Modern Astronomy
Unit 3: The Revolutions of the Heavenly Orbs
Unit 4: The Laws of Nature: Gravitation, Matter, & LightPart III: The Family of the Sun
Unit 5: The Earth & The Moon
Unit 6: The Family of the Sun