Possible travel insurance claim help

We are supposed to be going on holiday for Easter but there has been a case of scarlet fever in my twins nursery and I currently have 1 twin with a cough and the other has been sick in the night waiting to see what develops now

I'm preparing for the possibility of having to cancel the trip

Looking at the claim form it says I need my booking invoice and cancellation invoice. I booked flights online with BA as we are staying with family once we are there so it's not a package hol. How do I get these invoices when everything is online these days? It says no photocopies are accepted but surely they have to accept printouts of some sort?

Any advice?