First thing to do is get the pest control people in asap, doing it yourself can cause 2 things to happen, no1/ They could and probably would become active and sting, also you need to kill the queen, she sits in the net and doesn't come out at all, What happens is the pest control company (whoever it is) pump a substance in and around the nest ( WHEREVER you see them coming out/in if you cant see the nest) The wasps then take this substance into the nest normally when spraying the wasps are active and the stuff goes all over them, they take this into the nest then after a day or two the queen dies and the wasps either leave or die in the nest, I was informed that the nest we had was between the felt and the tile so we couldn't see it, they don't do any structural damage apparently, but if you can see the nest normally once they are dead and nest is inactive the council normally would take it away.