Steve, sorry for the late reply, I'm all signed up via my MSDN Premium subscription as a Store developer with all the Azure free stuff and VS2012 RTM. From what you've said I can see now that I tried the wrong combination. You must have the release of Win8 with VS2012 built-in (I think I saw that as a download). I have been confused by the combinations of releases and downloads.
There is no demand, so I'll wait for the "real" Win8 to hit on 26-Oct (my birthday!) and try some Metro development then. I'm still filled with unease about Win8, but I feel a geek compulsion to get something into the store. I have a few personally useful hobby apps which could be "metroised" quite well as a learning exercise. I actually am quite excited by the idea of the app store, but I still wonder how it will be managed to prevent it turning into a garbage dump. I hope you have qualified female behaviour consultants guiding you on the Keeping Score app!! Greg