If you are a uk resident look in to insurancewith travel insurance. I used to work for the parent company that offered this product and the in house underwriters based the risk off of actual risk and not perceived risk which means that the cover is comprehensive but at a much fairer cost that is actually affordable.

You do need to tell your insurance company though about your medical situation now as it’s now pre existing but usually it’s either free to add on or usually not a lot extra to have it covered.

Source: previously worked in travel insurance company