Social Realism Target Audience

From doing research into some social realism films, I can see that the majority age rating is 15. This means that when I think about creating my trailer and accompanying text that it should appeal to people ages 15 and above. If I was to create the actual film I would have to look into how BBFC classify the different films and ensure mine met the 15 criteria. However as I am only creating the trailer I need to make sure it is appropriate for all audiences to view so this means including little or no scenes with drugs in it and also ensuring the language is clean.

Adulthood is aged 15

Fishtank is certified 15

Ill Manors is certified 18