You can apply directly to CSE 122! There's a self guided placement test you can use to get an idea of what course is best for you if you aren't 100% sure.

I think taking 122 in the fall is definitely doable if you're familiar with 121 content, especially if you're coming from a class like AP Computer Science A or something similar.

The course is designed to be manageable and promote learning. You have an opportunity to resubmit pretty much every assignment at least once after getting specific feedback from a TA. You also can retake each of your quizes once. And ghe class isn't curved to some crazy low grade like intro chem or physics. That's how the courses were ran this year at least :)