I literally just finished P1 Biochem at MWU-CPG.
There were two categories of folks: those who had taken Biochem, and those who had not (I fell into the latter category). There were two major grade distributions: <92% (half or a third of the class) and the rest of us. Let me just say, there were very few Bs (and for our year, any D is failing).
I spent so many hours on the course material, easily twice or more what the biochem majors were studying. (Even though they insisted that the material was different & they had never seen a lot of it before.) As a reflection, a lot of biochem was simply "speaking the language" - I had to become fluent before I could even touch the real material.
TCA cycle was covered in half a lecture, but we were expected to know it - and the ramifications of changing anything affecting it / effected by it - in detail. (Playing devil's advocate: I do go to a 3 year, so our biochem course was 10 weeks.)
Knowing your undergrad biochem may not exactly cover the information in your P1/P2 biochem course, but you will be well prepared to study for it, which is most of the battle. Trying to formulate a study plan for a subject you've never seen before is really difficult.