I agree - I'd use the BRC manual as the basis and even number it in the same way so it's easy to find during an audit, then I'd audit the practices / work instructions / meeting minutes etc to make sure every point had some supporting evidence. It's then worth putting a folder together of supporting evidence (about a month before BRC each year so the versions are current) then you'll just rattle through the audit and also make sure your QMS is thoroughly audited every year - although note ideally the person writing the QMS should not be the auditor just to confuse matters lol!
I wouldn't bother including your HACCP in the Quality Manual though as otherwise you'll repeat yourself - just reference it.