4121 is quite a fun and interesting course. Did it 21T3 with Aleks and had a term long major project on anything you want and a final exam. The algorithms are very math intensive (stats and linear algebra) so it's easy to lose track during the lectures. Often I would just watch the recordings so I could pause/rewind. All the marks come at the end of the term so stay on top of the lectures and chip away at the project and you will do good

Check out last years course website with resources and lecture recordings as well http://www.cse.unsw.edu.au/~cs4121/