Doitsu pointed me to this fantastic font program a while back, BabelMap:
http://www.babelstone.co.uk/Software/BabelMap.html
Once you launch the program, you are able to use Fonts - Font Coverage. This should check all available installed fonts for a given character.
In this case, you can use the tool to look for which fonts have: 266D = Flat Sign, 266F = Sharp Sign.
Another helpful font which covers nearly all of Unicode which might be useful to use is the "Droid Sans Fallback" font. This is one of the fonts used in Android, and is released under the Apache License, and free to use anywhere. It can be grabbed from here:
https://github.com/android/platform_...ter/data/fonts
I used it in one book where I needed the author's names using the original Chinese characters.