Hi,
Your school will likely tell the Uni what they want to hear, and that is that you are on track to meet entry requirements - they don't want to mug you off because you're a grade short. Worst case scenario, they don't! Uni lecturers will look at your predicted grades, and make a decision on whether to offer you a place or not (depends on how many places they are able to fill) - because you're just a grade short I wouldn't be surprised if they offered you a place. Make sure your personal statement is really good, and that you have a good reference to better your chances.
Good Luck.