Has anyone terminal risked a cheeky week in Europe without Travel Insurance?

Hi

I have advanced metastatic cancer from cervix to lungs and am desperate to join my sister for a week in Ibiza this summer.  Best (and only) quote I got back was for £679 for the week!! 

I have applied for the government health insurance card - which I know won't cover flights home or all things - but I feel more than well enough to go for a week between chemo cycles and I'm sure my onc would back that up. 

Has anyone taken this risk or have a view on it?