It's really difficult online and sometimes requires a phonecall. Have you tried Staysure?

Hi Nevo, my dad has incurable prostate too.  Don't refer to it as terminal unless they think you have less than 6 months to live, which I don't think you will.  Try insurancewith and world first - both insured dad to Europe and America and he was 80 when we went to Florida. They even insured him recently having pneumonia!  £192 for him and mum for a week which I think is very good.  Don't know how good they are if you have to make a claim as thankfully never needed to.  Good luck

Thank you