Cashing in/selling insurance policy

soba

We've got endowment policies with the Prudential and Friends Provident. We keep getting letters from them saying that the eventual amount that will be paid will not cover the amount of our mortgage. However, we've mananged to pay quite a bit off our mortgage over the years, and we're thinking of cashing the policies in. We think we could sell them on, and today I've had cash-in values from the Pru and Friends Prov, but don't know who to approach and what to do next regarding selling the policies on to another person. I've been on one site and it's a very detailed form that has to be filled in - is it safe to give all the details?

I know this has probably been covered time and time again, but I did a search and couldn't find anything.

Thanks.