Of course it will be challenging. It's content you haven't done before, and it'll be presented to you quicker and you'll have to make your own time to do the work. It's not high school where you're babied along and if you don't do work you get a detention. If you don't do work, too bad - see you next semester because you may have failed the course.
Do the work, and you'll be fine. If you make time out to focus on it, you'll do fine. Your lecturers and tutors are there, and you can ask them to help you. Or you can make a study group with like-minded people.
Basically, it's not going to be that bad if you put in the necessary time and effort. You may fall behind, you may find it challenging. But it'll be a lot worse if you didn't put in any time and effort at all.