Its definately worth a shot. I recently got admitted into Oxford for my MBA and trust me a few years ago I wouldn't have even dreamt it. I'm a Nigerian, with about five years experience in Asset Management/Private Equity in Nigeria, mediocre undergrad GPA (3.34/5) and a 670 (mediocre) Gmat. I think the essays and the interview are the key to getting in to those schools. You can also strenghten your extra curriculars now while you have the chance. Your profile (if you can get the 700 score) should be competitive, u need to make sure your essays reflect you as someone that would add value to their class. You should also spread your net farther than just one school (i applied to Oxford, Cambridge and Cranfield and although i didn't get into Cambridge, I got admitted into the others).
My advice to you is to start thinking about your strategy now. When you do apply, you'll need to show how the MBA is the next logical move for you and how it'll add value to your career. If you make any career moves before then, you'll need to have a good reason for it and show clearly how it ties into your MBA aspirations.
My two cents.