Given your background (not a biologist or chemist) you would probably find the introductory material in a biochemistry "lite" textbook more accessible/useful than a hardcore text for specialists. As a co-author of a biochemistry textbook, I can tell you that there are essentially three different classes, or types of texts.
- Comprehensive textbooks, of which I think Voet & Voet is an outstanding example, are designed for biochemistry majors who will be taking a full year, in-depth course, typically in the 3rd year of their undergraduate studies.
- The general introductory texts are usually thinner, and are designed to whip through the same material in half a year--aimed at life-science students in other majors. Some of these books that I described as "lite" are further targeted to, for example, nursing, medical, or dental school students.
- The third category of text tries to be multi-purpose, and appeal to both markets. The current versions of Stryer and Lehninger fall into this class (they are both excellent in my opinion); the instructors can cherrypick the readings if they want to use the book for a half-year course.
Voet, Voet, and Pratt (mentioned in the comments above) is a very good diluted version of Voet & Voet. As you can also tell from the comments, different texts have different flavors, and so which one is best depends on the reader.
It sounds like a more general "concept" based book might be useful for you (to provide background and context). The very thick "Molecular Biology of the Cell" by Alberts et al., has a lighter cousin named Essential Cell Biology which would be well worth looking into.
Keep in mind that when tackling a university-level biochemistry course the instructor has to assume that you have passed university level introductory courses in general chemistry and in organic chemistry. Biochemistry majors typically complete full year courses in both these subjects, as well as a watered-down version of physical chemistry.