Is it really hard to stay in University when you just barely got in?

Not really. Most universities loves to get your tuition money. It depends on the university,and how enrollment looks. If your grades are not up to par the first semester you will be put on probation. If they are not improved upone the second semester you will be put out for either a year or a semester. Once you have met the requirements universites don't hold a flag over your head just becaue you narrowly got in. Please rate this answer.

If you find you are having difficulties, go to your advisor and ask for tutoring help. Sometimes there are study hall situations set up with student advisors - at least there was where I went to college. Good luck to you!