Film Classification

We initially planned to make our film a 15-18 classification, but once we had edited, we noticed that we used cocaine ( wasn't real cocaine) in our film which made us think that we would have to make it and 18. We talked to our teacher and she said the " If you dont show anyone taking the grugs it can be a 15" and as there arent any clips of drug taking in our O.T.S we can leave it as a 15.