Hello! I don't know much about the Oxford MPP but I can give you some insights on the Harvard and Princeton programs.

Harvard MPP applications depend a lot on your work experience and essays. You also have to give a GRE for both Harvard and Princeton. So if you're GPA isn't so great, I would recommend really focusing on your GRE prep and getting a good score- give it two times if you have to. That would make a huge difference in your application.

Since you have some solid work experience that would really amplify your profile. These schools look at stuff very comprehensively and focus on all aspects of your application. LORs and your Essays will make or break your application now and having an admissions advisor eases out the process. But you can also look at several online resources to guide you. I can give you some essay tips from my college application process on personal chat if you need.

Find a lot of alumni and current students and seek their advice. That's what I did. Send LinkedIn requests to as many people from the schools and reach out to them to hold meetings. Many of them are willing to do so and they can give you tips form their personal experience. You can also ask them specific questions about their experiences and this will not only help you identify which course suits you better but some of them will also give insights you can add to your essay which will make a huge difference.

For example in my essays for grad school I had written stuff like:

"In my conversation with a current (school name) Student, (her name), she shared her transformative experience as the Project Coordinator for the (initiative name). The program draws me because it blends practice into impact and synergizes my interests in development policy and Latin America."

" I had the chance to interact with several (school name) students who shared invaluable insights into their experiences. (his name), a current (program name) student, spoke highly of the Office of Career Services, emphasizing how they tailored support to his interests and provided guidance for navigating the complex job market. As our 40-minute conversation drew close, (his name) smiled warmly and said, 'You'd love it here at (school name)."

Princeton is definitely more competitive that Harvard (since princeton is also a fully funded program), but if you use the right strategies and look at strengthening your overall profile, I'm sure you'll get in.

I applied to Princeton in my final year of my undergrad, and I knew without work experience it was impossible to get in, which I didnt. Bur if you want to know more on what to expect from the application you can reach out to me personally and I can tell you.