i work in the insurance trade, you can cancel your insurance within 14 days
however you will be charged for time on risk (ie how long you have been insured for)
your insurance company may also claw back some money if you have been given a discount
you may also have to pay a cancellation fee
it will be in your terms and conditions, and if you did it on the phone fsa requires that these terms
will have been read out to you and that you accept them, if you did it on the internet you would have had to tick a box to say you have read and agree to these terms