I did the MSc in Adv Computational Methods at Imperial and it was definitely hard work, but not unmanageable. I did my undergraduate degree in the US, so the biggest difference for me was that the final exams were often your entire grade. This meant that the course required a lot of self motivation to prepare throughout the semester for the final exam.
I recommend trying to find a group of people to study with early on. This is so crucial to getting through the exams and makes it so much easier! I'm happy to answer any other questions you might have about Imperial or and Aeronautics department
