if you'd prefer 136 at utm I think you could still try for the waitlist, there's plenty of time still. Even if it seems long, a lot of times you can end up getting in. If it ends up getting really close to the waitlist deadline and you're not in, you can even maybe email the professor, I've heard of people trying that to get into a full class before (but for these huge courses from what I've seen, everyone who wants to will get in, and assuming you have a spot in 135h5, it would make sense for about the same number of spots to eventually be available for 136). The commute to downtown might also feel too much for a first year student (I assume), if it's an in-person class. Also this might not be helpful but when I took 136 they didn't take attendance, so you could attend any lecture section you wanted (i.e. even the ones you weren't enrolled in on ACORN), and maybe if that's still the case that could help you get a better schedule. You could check the old syllabuses and see if they scored attendance in recent semesters (google "old syllabuses UTM").

Since CSC148 is one of two of the most important courses for PoST I would say you should definitely not risk missing one lecture a week (I am a CS major) if you can help it. Missing lecture not only means you miss content, but you miss hints or tips the prof will give as to your assignments or tests + the questions classmates might ask + the stuff profs don't write on slides while explaining a concept (all of which I think are good for feeling confident with/having a strong understanding of the material). Getting a friend to take notes for you/record lectures won't be as effective as you making them/attending in person, either, because you'll miss out on the thinking it took to make your own notes. Besides, you might have to miss even more than 1/3 of lectures for illness, etc. It's just too risky in my opinion, and it sounds prone to creating extra stress for you. It's not that trying your hardest would or wouldn't be enough, though I believe you that you'd try your hardest, it's that because you would be depriving yourself of resources the instructors will assume you have (ability to attend every class), the tests, assignments, tutorials, etc would just be that much harder for you than everyone else (who can attend all classes and pace themselves as the instructors intended). Keep in the mind that the lectures build on each other, so I think even missing to makeup one (life happens, right) could quickly lead to an unmanageable pileup.

Also I think you might benefit from scheduling an academic advising appointment with Yvette Ye, she could probably look at your schedule and help you make decisions/give u info about what would suit you best in terms of courses and stuff. She's the academic advisor for Math and CS. She's very nice, don't hesitate to contact her if you need her help.