The main critical illnesses are having a heart attack cancer and stroke. Fortunately, as medicine has improved so have your chances of surviving a critical illness.
Given that most UK families are 1 month away from not being able to pay the bills, can you afford not to insure yourself for this risk? By purchasing critical illness cover you buy peace of mind knowing that you can take time off to recover without the stress of how bills will be paid.
Critical Illness cover costs more because you are more likely to suffer a critical illness than you are to die during your working life.