Gresham College (London) provides free public talks on a wide range of categories:-
Art and literature / Business / History / Law / Mathematics / Medical science / Music / Politics / Religion / Science / Unusual
There are many Astronomy topics presented in the Science Category and you don't need a PhD to understand / appreciate them.
Talks can be viewed on-line or downloaded, and you can also print a transcript.
You can sign-up to receive e-mail notification of the upcoming programme.
http://www.gresham.ac.uk
