There are third party liabilities that insurers can't dodge if they accepted cover, even if it then comes to light that policy terms were breached.
Doesn't apply to many insurances.. car, plane and ship principally. It's to protect everyone else who is an innocent party (normally who you hit...
Not really. The insurers will still be on the hook for liability claims. If you crash into someone in your car and it turns out you weren't qualified to drive, your insurers don't need to pay you anything but will still have to pay the people you hit.
The pilot's insurers will pay less, but...
It's a single engine plane, at 5,000ft (so uncontrolled airspace), in the dark, flying VFR. Given the distance, this is not a straight forward, jump-in-a-plane-and-go flight. Call me old-fashioned, but if I have to navigate by landmarks on the ground and look out of the window so as not to hit...
For a single engine plane, Nantes to Cardiff is quite a long journey [close to 3hrs], but you can see why someone would chose a private plane over trying to do that journey any other way.