This subject is not for the faint of heart. I come from a physics background, but I found the subject difficult from the first lecture.
You're introduced to tensor notation that (I found) is difficult to grasp, and the problem lies in not having masters level physics subjects as prerequisites (i.e. General Relativity and Quantum Field Theory). The lecturer tries to get around this, but (in my opinion) it didn't work.
Due to the difficulty of the content, the assignments were changed to summarising the lecture notes and expanding on calculations given in Tong's notes (and a chapter from a textbook).