It is a 90 day report you will need to do, not a renewal, no fee. The first report must be done at an Immigration Office, the following reports can be done on line. As far as insurance goes, I'm not sure about short period policies, but why not pick a policy and select monthly payments and then just stop paying when you don't need it.
I was with PC and they denied a large claim for a total thyroidectomy, because of what they classed as "non disclosure". This was because after requesting my Australian medical records, they found I had been treated for a painful shoulder, many years ago and shingles that I had not declared on my application.