Fiona,
I agree both with Don & Stephen. There doesn't seem to be much problem at all with messages to local businesses as long as your message is appropriate to the recipient, it stays fairly short, and you don't try to "sell, sell, sell!" with your first contact. Conversational. Pleasant. Business-like.
Stick to those parameters, and you'll have no problems.
Best Wishes,
Jim Erskine
Homeway Press
Local Business Ideas worth a look and a "hmmmmmm......"