This may be of some use to others here
Just out of curiosity I rang my travel insurance company yesterday to enquire about a policy that would allow me to spend longer periods of time abroad.
Now, my current policy is an annual one but it only allows me to be out of the country for a maximum of 90 days at a time. What they suggested was to take out a Backpackers policy which would give you up to 18 months continuous cover, the only stipulation being that you could not return home within those 18 months for a period exceeding 14 days. When the 18 months are up they said you could apply for an extension which they would approach their underwriters with for approval (I doubt it would be approved if you had made a claim).
May be worth a look for those planning a longer stay or as a stop gap before you get a policy over there.