…is not straight forward!
fortunately I tried with a company called InsureandGo. and they charge an additional premium, ask you a load of questions to see if you qualify. and if you do then they will insure you with an additional policy.
I think the most important question was whether I had, in the last 2 years, received an inpatient treatment. Fortunately all of the medication I had received was given as an out-patient so I passed the checks and I was able to get. travel insurance with them and at a reasonable cost. I was sent a special certificate to prove that I had the additional cover-their silver cover.
I took this insurance out for a number of years and it is only now with my recent full episode of pneumonia that I don’t think I would be eligible anymore.
I have however in my recent internet research found a company called able2travel that specialises in offering travel insurance for people with medical conditions. Definitely worth a look, especially with the threat of brexit looming and the concomitant invalidation of the European health insurance card (EH I C) which gave you access to health provision overseas throughout Europe!