As a note, I'm well aware most applicants in the UK have never attended summer programs in their lives and neither this is a necessity, or taking college-level courses is enough on its own.
I plan to take Intro to Political Theory and Comparative Politics at the Harvard Secondary School Program, which selects its students according to their academic standings. I was wondering if doing a second year of HSSP and taking Game Theory and Intro to Ethics would be too much since the former requires a minimum knowledge of Calculus, which we cover in 11th Grade. These kinds of programs actually cover the recommended readings of Oxbridge and let you write a dissertation/essay of 5-10 pages hence I can show the admission officers that I really care about the subjects I'm planing to study in the future.
I am also participating in the European Youth Parliament, Model United Nations (MUN), and Debate team. I am also planning on joining The Hague International Model United Nations. These experiences may prove useful as they demonstrate my interest in politics and my ability to think critically.
Not looking for snarky comments, please keep it civil and respectful.