Barrie,
I think Matthew Hindson has some fonts that you could use. I was looking at his Accidentals font last night using the Windows 7 font viewer tool -- it had the sharp, natural, and flat that you're looking for. Some of Matthew's other fonts were garbled (for lack of a better word) in the viewer i was using. In at least some of the fonts, he includes documentation for how to use the font.
http://hindson.com.au/info/free/free-fonts-available-for-downloadThere's also a very complex set of fonts called Bach that Hindson references from his page.