Modern languages isn't as competitive as other courses at most universities (which is sad!), so I don't think resitting exams will harm your application too much. Of course, it's not ideal to have two Cs in languages, but if you're predicted the right grades and have a good reference you will definitely stand a chance I think.
If you're still unsure, you should email the admissions officers and ask them, because they'll know for certain. You also have to remember that grades only form one part of your application - you have your personal statement, reference and GCSEs (although these aren't so important outside of Oxbridge), too. Plus, AS grades aren't as important as A2 grades, so I'm sure you'll have a good chance!