Talk first with your homeowners' (or renters'?) insurance company. Sometimes you can just add a rider to that policy.
In any event, get yourself a good umbrella policy too if you don't already have one.
In our case, when my wife had her professional pet sitting business, we had to change insurers because our existing homeowners' policy would not insure us with a home occupation on the premises (even though no clients ever visited us at the house -- the "business" within the home was just an office).
Be prepared to answer questions about the business equipment on the premises, its value, how many customers are expected to visit each day/week, etc.
If your existing agent is employed by the insurance company itself (i.e., not an "independent agent"), you may wish to find one. For example, with auto insurance, Allstate and State Farm employ their own agents, whereas Mercury, Safeco, and Progressive are examples of companies that use independent agents.
I have done business with my independent insurance guy for about 12 years... He's great. When I told him about my project, he advised me to contact him as soon as the permit is issued so that he can get my policy updated to include the value of the project in the policy.
Over the years we've had to switch companies a few time, but he remains our agent, and it's always very competitive.
Kudos to Mrs. Kendale for keeping you on top of this stuff.
--Keith
We shall begin our investigation immediately. Perhaps this might be a useful topic/sticky/resource for others as well?
Somoehow I think I ended up with Japanese! 