Hi Anurag21
I admire your ambition studying the IMC at age 16 however i would note the following. The IMC is essentially a regulatory exam along with a whole host of other regulatory exams without which you cannot perform 'set investment functions' in the UK. If your ultimate goal is to become an employee of an investment bank I would suggest that you try to achieve a 2:1 or preferable a 1st from a top 10 university, preferably in a maths,science or economics. I would also suggest that you aim to get an internship each summer during your degree (which you seem to have cottoned on to).
Personally I would put all my effort into getting into the best Uni possible and achieving a 2:1 minimum and getting an internship during the summer between years 1 and 2 at Uni.
I would also not get too hung up on exams at the end of the day when you enter the work place you will need to develop a whole host of new skills which no exam can teach. Working with other people, negotiating and the ability to take on/manage new clients to the firm (to name a few).
Also do not get hung up on a job in banking it is not for everyone, I have seen people burnt out before the are 30, make themselves ill, what is that for? where is it going? and you can leave your morals at the door.
and last of all don't forget to have fun, that's the most important thing