Doing a third year of A Levels.

I just finished my second year of sixth form. At the end of the two years, I achieved A*A*A*, in Maths, Chemistry and Biology, and also an A in AS Classical Civilisation (so I won't be doing any resits). Having changed my mind over the second year about my choice of course (from Chemistry to Chemical Engineering), I have decided to stay at college for one more year, where I will be studying AS and A2 Further Maths and also AS Additional Further Maths. I was wondering whether or not this extra year would disadvantage me as an applicant, despite having gotten grades that exceed the minimum offer for the Chemical Engineering course at somewhere like Imperial or Cambridge?

As far as I'm aware, no you won't be disadvantaged because they're new A Levels meaning that you're not using three years to complete them. You also got A*A*A*a which makes you perfect for an application. You should call them up and explain why you're doing two new A levels and see what they'd say about that.

You should be fine! As long as you do great in FM and AFM you should be able to do it! Good Luck!