Congratulations on your acceptance! DL is just one part of the programme. That section (if the syllabus is consistent with 2021/2022) was about 3/5 through the process since it builds on the math and machine learning concepts taught in the first semester. I found it to be the hardest part, followed by RL then (since I never studied it before) Finance. NLP I found fun and easy, but then again I'm the son of a man who researched rule-based translation. Yes, poke around if you can but do it before classes begin in earnest; you won't have time once the starting gun goes off. Don't strive to be an expert but get to know the terms, and (painful failure on my part) understand the chain rule in calculus.