Picketywitch - new to the forum and seeking advice on travel insurance

Hello there, I am new to the forum and I would like advice on Travel Insurance please.

My husband had a bladder cancer tumour removed and has completed his radio therapy treatment.  We hope to go to Corfu in September but I am not having much luck with finding travel insurance.  My travel insurance with my Nationwide account will not cover my husband as he has other medical conditions too.  I have had one quote of over £3000 and several just shy of £2000.  Can anyone please recommend a reliable reasonably priced Company or Companies that I can try.

Many thanks