Getting into LSE/ Oxbridge as an American for MSc Economics and/or MPP

Hi,
I am currently a second year student at Occidental College, a small liberal arts college in Los Angeles, and I am wondering what I would need to do to be a successful applicant to Oxbridge or LSE Msc Economics program.

I currently have a 3.5 GPA (after three semesters) with a double major in Economics and International Relations, and a minor in Math.

Economics GPA: 3.43

International Relations GPA: 3.57

Math classes taken so far:
Calc I (B-)
Calc II (taking now)
Statistics (A-)
Planning on taking: Linear Algebra, Multivariable Calc and Probability

I want to go into economic policy in developing countries, and work for a think tank or NGO as a career.

I have had an internship at the U.S. Congress in DC between my freshman and sophomore year.
I have had various leadership positions in political clubs on campus, as well as a micro finance club for small businesses in developing countries.
I am the president and founder of a branch of a millennial organization that seeks to promote bipartisan solutions to problems facing our generations (I have drafted a lot of policy proposals and done a lot of research for the club)

I am currently looking for internships over the summer at think tank, central bank, or NGO.

Would Oxbridge/LSE take me with a lower GPA (upper 2:1 range) instead of a first class honors GPA, but with lots of great work experience, LORs, and solid GRE scores (when I take them in the future?)

Also, I am an EU citizen (Polish citizenship). Does this help or hurt me?

What can I do to have a stronger application?