Your predicted grades are whatever grades your teachers feel like predicting you, there is no formula. As far as I am aware, unless you make a special request to the exam board your grade is calculated by finding the highest possible grade you can get in maths, and giving you this grade with the lowest possible modules, and then putting everything else into further maths. Maths is guaranteed to be the best grade you can get, and they will do their best with FM as well. Also, Warwick in the past have made offers to most applicants, preferring to do it this way and have a higher offer. I see no reason this should change this year, especially since they have upped their standard offer.