I’m a bit confused. I’m not sure whether your issue with this is with the works, with the strata manager, with the landlord or with your insurer. To me, at face value, this seems like a perfectly legitimate request from the strata manager and certainly no grounds for a rent reduction from your landlord. As you yourself have said, sometimes works need to be carried out. These things simply happen, it’s nobody’s fault.
And on the question of insurance, just give your insurer a call and discuss it with them. You might be surprised how understanding they turn out to be.