David,
Gresham College London puts on free public lectures about many subjects. There are lots of Astronomy lectures in the Science section. You can download each lecture for later, or watch on-line, and you can download PDF of the text. The current Astronomy lecturer is Professor Carolin Crawford. She is not heavy on the maths / science - it is interesting public extension.
http://www.gresham.ac.uk
Also for free, there is Astronomy 160 and 161 presented by Professor Pogge of OHIO State in 2006-07. You can Podcast the lectures and download text.
http://www.astronomy.ohio-state.edu/~pogge/Ast161/
http://www.astronomy.ohio-state.edu/~pogge/Ast162/
And isn't "Up" a wonderful side to find.
Cheers