"I have a natural tallent in maths (apparently!) and I do not feel I would struggle with the aptitude tests"
Doesnt sound like you will have any confidence problems my friend!
They look for the confidence side of things not only from your interview, but from your group excersizes, if you aim to get along with the people in the group and give suggestions as well as taking suggestions, this would take on a 'team player' feel. You dont have to be super confident to be a Pilot, in fact you need to have a balance, confidence enough in your decision making skills whilst being open to criticism. Over confidence is one of the worst attributes a pilot, and indeed any person, can have. It leads to arrogance and, believe me, no-one wants to multi crew with an arrogant power-mad Pilot. It leads to a cavalier attitude and ultimately accidents.
I think if you went into your interview and kicked back, bragging about how wonderful you are, you would be out of the door much quicker than someone who had the necessary skills and talent, but was a little less assertive than the others.
Best bit of advice, as I always say, is BE YOURSELF. Then you will know for sure whether or not this job is right for you.
Good luck
(ps. dont underestimate those aptitude tests, they are pure evil and I would never want to do them ever again.
ever.)