Its probably not much different than the other standards that you have worked with. How did you go about learning them?
Like you said, reading the standard is probably your first step. As you are new to food you may need to seek out aditional information on subjects that might not make sense to you as you read the standard. This could be on forums such as this, on-line literature or article, or different trainings. You will need to take a HACCP course. At some point in time you COULD take the BRC lead auditor course. I wouldnt suggest doing this right as it is probably a little advanced for someone brand new to food MFG.
Since you are familar with standards and auditing, I dont think that learning/auditing/ implementing BRCGS is going to be your challenge. I teach people with zero relavent experience to do it all the time. Understanding the actual science behind all of it what is hard for someone with out education or experience.