Help re uninsured house, please

Hi Everyone, I’m hoping someone can advise me, please.
We’re having a kitchen extension- fairly straightforward ( I hope!) - the builders are knocking down the poorly built present extension and rebuilding it. Whilst they do so the entrance to what remains of the rest of the kitchen will be made secure with boards and there will be no outside access through the kitchen- hope that’s clear!
Our problem is that our present insurance company ( building and contents insurance) have refused to cover us whilst this work is ongoing- we’ve had to cancel the policy- and we can’t find another company to insure us. Has any one else had this problem- I’m dreadfully worried to think the house isn’t insured. Hope someone can help, thank you