Hi wolfie hope you're ok.
If it's the metal in the body issue (the other thread) then there's nothing wrong with flying, just don't go near a magnet :D
The doctor will give you a cert stating your well enough to fly. As for insurance you have to declare your illness and it's then upto the insurers on whether or not they'll take you on.
My guess is that any costs arising from your current illness won't be covered... at least that's what my last insurance stated.