You are thinking of releasing some of the equity on a house which you own, is that correct?
If you are not planning to leave your house to anyone in your will, then why not? My dad did this, when he died mother benefitted and stayed in the house (which I know won't apply to you), but it was only when she moved into a home and the house was sold that the equity lenders took their chunk out of the sale proceeds. It seemed a good arrangement to me, but I guess you have to pick your company with care.
Don't just sign up with the chap who comes to see you next week - get a couple of other quotes first, see some more chaps!, then you can pick the one which is best for you.