SFML, just because it uses classes, doesn't mean you have to use it in a OOP programming style. I would recommend SFML regardless of whether you use OOP or not (or even if you don't know what OOP means).
But... SDL is also good. They are both good, and SDL might be a bit easier to understand at the forefront - but maybe not. The real important thing is sticking with whatever choice you make without bouncing back and forth every time you encounter a problem.
[Edit:] You only have two months? Jeesh. Go with SDL then.