I'm naturally quite a risk adverse person so if I can insure against something I generally will however critical illness cover is such a lot of money (particularly if you smoke) that it seems the chances of it actually paying out in the event of illness are so slim they outweigh the cost of the cover.
I mean, if you've ever been to the doctor for an ache or pain, is ist going to bite you on the arse in the event of a claim in that it would be classed as an existing condition, even if it wasn't?