I work in the residential side of a boarding school. I've been told if a student on the first floor refuses to leave the building when the alarm goes off to use the stay put policy and remain with the child and the fire service will be directed to us first.....is this acceptable? 

It all depends if the construction of the residential side if a stay put policy is acceptable and even then certain residents may need to evacuate, dependent of the fire situation. If a stay put policy is adopted then all are subject to it and you cannot have full evacuation and a stay put policy combined therefore your suggestion is unacceptable.

In my experience there is few people that would remain, if there is a safe means of exit and a fire is licking their rear end, if this did happen I would use force.