I am an international student and am in Year 12. Are the entry requirements for unis going to different for me because I'm an international student?
Not really - or at least for UK universities as far as I know. You should be getting the equivalent or the same grade and subject requirements as the home students. If you are studying for different international qualifications, universities might seem like they are asking for different grades for the qualification that you're studying for, but they should be roughly (if not exactly) the same.
On the other hand, if you are based in a less socio-economic area in the UK with poor schooling then you might be eligible for lower grade requirements (but just by a smidgeon).