Travel insurance is relatively inexpensive. Coverage applies to specific covered conditions and has specific dollar benefits.
It's important to carefully review the policy. Make sure it covers what you think it covers. Many policies don't provide coverage if a vendor (airline) goes out of business. Policies don't generally pay for airline tickets on another airline if your flight is cancelled. The policy will generally provide a specific dollar benefit (daily max/policy max) to help pay for hotels and meals.
According to the link you provided travelex will cover H1N1
What's not covered is a traveler who wants to cancel a trip if WDW has an outbreak of H1N1 and the insured doesn't want to take the risk of being infected.
Access America has a similar exclusion BTW the terms are until December 31, 2010
What's important to note is some plans require your doctor has to quarantine you and/or says your not allowed to travel. It doesn't matter how sick you think you are if your docotor says you can travel you don't have coverage.
Insurance companies won't allow insureds to use the fear of swine flu, or a self-diagnosed case of H1N1, to re-write a policy to one which provides cancellation coverage for any cause.
edited to add a few carriers have a big "loophole".
Avoid those carriers