I'm not a French student but grade wise this was exactly my position last year, I went through with abb from L6 but with resits and resits somehow bumped them up. If you love Durham then I'd say go for it. Like everyone said, put your results as pending on your ucas form and as long as your predicted grades are what is required you should be fine.
A word of warning though my friend applied for French with predicted grades AAB, B in French, which although was all they asked, didn't get an offer. Of course it could have been her personal statement etc but I suspect Durham may like the triple A in predictions, or at least an A predicted in French. This isn't fact though, just my suspicions from this one experience.