How much rent would we have to pay?

we have 3 children and live in a 2 bed council property my ungest is 18 months old will need to go in to his own bed soon but there is no room, so we need to move in to a 3 bed property, there are no 3 bed council propertys on the council list so we going have to go private my partner works 18 hrs a week, was wondering how much help would we get with rent, property we are looking at the rent is �525 per calender month, but dont want to move before we now how much we will have to pay, we live in stoke on trent ...thanks