Target audience/potential age rating

The target audience of my thriller will be a British (national) audience, rather than an international audience because I think a national audience will possibly get my thriller more noticed/known, as a national audience is a smaller audience compared to an international audience (which has a wider market).

The potential age rating of my thriller will be an age rating of 15 years old, as I think my thriller will appeal to older teenagers, and young adults. I think the age rating of my thriller is suitable to 15+ year olds because of the adult theme of my thriller, and the language that will be used in my thriller.