In the UK cover and costs vary tremendously depending on what you need and what your medical history is.
It's an unfortunate fact that, whilsy you are fit and healthy, premiums will be the industry average, once you are treated for anything under the policy, premiums shoot up, often to unaffordable levels.
I don't think that it's ever been proven, but the media have alleged that once you need treatment, such insurers boost premiums to unaffordable levels because they all rely on the majority of us never claiming to enable them to make a profit. Once we make a claim, that's the profit from the annual premium gone.