The challenge is that there are a lot of international students all chasing the same funds. Your GCSEs & A-level predictions put you in the top tier, but there are plenty of students who have similar marks with higher test scores (and/or something else shiny on their CV). So, if you can manage a 30+ / 1400+ by all means apply, b/c you never know.
Based on what you have said about what you are looking for in an undergrad experience, I wouldn’t be sold on your loving Cornell. Bowdoin will be as tough an admit as the others above, but (guessing) it would be closer to what you are looking for (esp if you are cold tolerant!). fwiw, the business school at UPenn is famously cutthroat, but the few IR types that I know there are very social and friendly, but I am by no means pushing it.
Another that may have slipped by your radar: Dickinson College, which meets need, has a pretty international outlook, has a DC semester option, and does not put as much emphasis on ACT/SAT as some do. You would be a strong candidate (esp if you can get your test scores up a bit).
Have you tried the SAT? some people seem to do noticeably better at one test format than the other. the