It doesn't. Half of the book is not even in C (The book is half java (simpler interpreter), half C (bytecode compiler + VM)). The book explains what the code needs to do very very clearly, so even without looking at the C code you would gain a lot of value.

I've been teaching a class the lasts few weeks with a dozen people who have never programmed before using that book. It's going well.

I have the book but haven't gone through it. When I do eventually get to it, I will probably ignore all of the implementation languages, instead choosing something like F# or Racket. You could do something similar.

I think you should at least understand the basic concepts like loops, variables, pointers and whatnot before trying to follow the book, otherwise it may be a little rough.

You definitely don't need any expert knowledge though! Also following the book will increase your C knowledge as you go (at least in the second half).