First year International Relations student here!
Funnily enough, I answered a similar question a week ago, so I will just copy-paste the list of A-levels I wrote back then and add some other thoughts
In my opinion, the most relevant A-levels for International Relations are:
- Government and Politics
- History
- Sociology
- Foreign languages (French, German, Arabic, Japanese, etc)
- Philosophy
- Economics
- Geography
Any other subjects like Mathematics, English Literature or Psychology work.
Personally, my ideal combination would be Government and Politics, History, and a foreign language, Economics or Philosophy. For a fourth subject, Sociology or any of the three third options I mentioned (foreign language/Economics/Philosophy) would be of great help. Geography is fine and it could be useful if the modules you will take have a use for it, but trust me when I say that you do not really need to know anything beyond basic geography for International Relations. In fact, I do not believe my knowledge of geography has helped me at all ever since I embarked on this degree, while studying Government and Politics and Sociology helped a lot.
Having two facilitating subjects is good, but not necessary if you would rather study something else. I myself studied Government and Politics, English Literature, Psychology, and Sociology and got an offer from Exeter, so I doubt only taking one facilitating A-level was that much of a problem. Doing an EPQ is not mandatory either (I did not do any EPQ and here I am, in university studying international relations), so only do it if it is something you would be interested in.
I highly disagree that extracurricular activities are the most important aspect. Your grades matter most. No Russell Group university will let someone in with BCC because they did an immense amount of extracurriculars, after all. I do believe that extracurricular activities are important so that you stand out (I myself did quite a few extracurricular activities), but grades top them any day. To be completely honest, I think your evidence of wider reading is more important than extracurricular activities as they are very useful in order to show your interest in the subject.
This is how I would rank the importance of the components of your application for International Relations:
- Predicted grades
- AS grades (if applicable)
- Reading
- Subjects studied
- Extracurricular activities
- Everything else
Again, this is just my opinion, but it is based on my own experience.
Hope this helps and good luck!