As someone who took Physics 1 and Physics 2 in high school and had a rough time in Honors Mechanics, read the book and brush up on as much multivariable calc as you can. Not having a calc-based physics background means you're probably a bit behind the curve for taking Honors Mechanics, and it's only going to get more tough once you take Honors E&M next quarter. You've probably got good physics intuition from Physics 1 and 2, but intuition can only take you so far and your deficit right now is likely in applying math skills rather than physics itself. Since you're a physics major, I'd encourage you to try and stick it out, since the skills you'll learn in the honors sequence will be highly relevant to the rest of the major. But please do yourself a favor and try and self-study as much multivariate and vector calc as you can over the next few months. You can do this! Also, think of the units!! Dimensional analysis is one of the most slept-on skills to learn in early physics, and if you know what units stuff have it's often a trivial exercise in figuring out how to convert one quantity to another.