I’m so sorry to read this and hope that you both feel better soon.
Regarding the insurance, I recently had to claim from my insurers after cancelling a cruise beginning of December - not Covid related but a close relation fell ill and was hospitalized.
This was a FO cruise, and the TA sent the cancellation invoice within 4 days. We had to cancel a Cunard cruise about 5 years ago, same TA and the cancellation invoice was again sent within about 3-4 days. I can’t imagine why P&O should be any different.
Sorry about the parking. With the Cunard cruise, I remember we ‘paid’ for the pre-hotel stay by redeeming a free night with a booking company, but were unable to claim for that, so sort of similar to your situation.
Once you have the required documents, the claims process was quite straightforward so don’t be alarmed. In my case, with Staysure, I had to upload all relevant documents but I think it’s also possible to do it by post. It then took a week (5 working days) for them to provide a settlement offer which was exactly what I was expecting.