Hahaha, i don't know where to start. But if you are interested in programming or electronics, computer science is not that hard. When i was finishing high school a lot of people were saying to me "don't go there, you suck at match, you can't be programmer bla bla bla... ", true, i hated maths at high school and i had bad grades from math tests aswell. But i completed my exams at both Discrete Mathematics 1 and 2 from first try. Actually i passed all of them from first except Arhitecture of Computer which is a lot of theory and exercises aswell, but they are not that hard to learn, some basics convertions from numeral system to another, exercisese from Hash Memory, and MIPS was hardest (at least for others). We had like MIPS projects for extra points, some friends said they needed like 2-3 days to finish them. I actually completed it for like a hour (i didn't had prior knowledge in MIPS).
We had some other Informatics related subjects, which were not that hard too. We studied Photoshop, Scribus, ImageMagick and some stuff. Big percentage of the students finished these exams.
Both mathematics were kinda hard (we were like 100 from 1000 to pass DM2). Object-Oriented Programming was same, only 15/100 from my group passed on colloquiums (if you pass on colloquiums, you don't have to go to exams). And like 10 of them got like 6/10, few 8/10 and me 10/10 xD
Even if you miss a lot of classes, you can still pass the colloquiums without any difficulties if you are passionate enough to practice.
Students from other directions (gymansium, medicine, musicial and etc) in High School tend to study a LOT, but they still fail on colloquiums and exams. Because they all study, how to say it... on mind. They try to remember all, instead of puting it in use.
If you find the right way to study and if you are passionate, as i said, you don't need to study a lot. For example i've only attended 30% of the clases, i was hanging out with people (since i was staying in Student Housing), playing cards, going on coffees and etc. And still i got pretty good grades for not that much of studying.
I just want to say, study what ever you want, if you like it - it is going to be pretty much easy to finish it and to have fun while you are studying.
And most important tip: Don't rent apartments, go to student housings, you will meet more people in one student year than you have ever met. That is the best part of studying in other cities.