If you are here at all, you have the ability to succeed. Computing is a fascinating subject. If you are interested in it, you should want to do the work, and if you do it you'll have a happy hassle-free time here. It is used in later years. These are mainstream subjects.
Theoretical methods are increasingly important as computing becomes more sophisticated.
But my friends at other universities don't have to do all that. This is a demanding course. As I said, students leaving Imperial take up positions of authority in computing. They have to be able to see things abstractly and reason about them rigorously. Learning something won't kill you, after all.