The wonderful thing about BRC (and other GFSI approved schemes) is that it tells you what you have to do, not how you have to do it.
If you wish to include all of the requirements of 3.4 in one document/policy/procedure, you are certainly free to do so.
Let's say you choose to have a document/policy/procedure called "3.4 Internal Audits".
As long as you say what you are going to do to meet the standard in that document, that's perfectly fine.
"Say what you do, do what you say and be able to prove it".
For 3.4 I have a document that discusses the internal audit of all the sections of the standard, and how that is accomplished.
The standard requires a schedule of internal audits "throughout the year", so I have a separate document that is the internal audit schedule.
The standard also requires that in addition to auditing the standard, you do inspections of the production areas at least monthly.
I have another document that describes what that means, who does them, what is required, what is done with the results of the inspections and how they are communicated.
Theoretically, you could put that all in one document, but in general practice, that would glaze over peoples eyes and they would never read or understand the entire document.
As long as you are addressing the standard where it says "there shall be a program" or "there shall be procedures"....and have the documentation to show that you are actually doing what you say you are doing, you are good to go.
There is no right way or wrong way to write procedures or policies under BRC. You just need to address the requirements, and have the documentation to back up what you say you do.
Marshall