Getting out of a PPI deal - would this work?

Question for anyone knowledgeable in the ways of purchase protection insurance policies.

If you found your circumstances changed such that you were ineligible to claim under the policy, would that entitle you to demand its cancellation, on the grounds that the company intended to breach its contract?

An example would be if you went from a salaried to a freelance position. Freelancers can't usually get redundo insurance, so if the insurer wouldn't have sold you the policy had you been a freelancer at the time, and now won't honour claims, couldn't you argue that they now intend to breach contract, so it's null and void?

I don't have any such policy, but I am wondering if this could be a way to get a policy cancelled mid-life i.e. after the cooling off period? - which is an occasional question here.

I suspect the answer is that you might technically be able to do it, but only at the cost of having the associated loan called in.

Anyone know for sure?