GDL Requirements? I'm an International student

Hi everyone. I am currently pursuing an undergrad degree in International Business Management at HWU and am currently in my 3rd year of study. Although, after this I plan to do a GDL, but was a bit confused about the requirements. Do I need an honours degree, or do I not i.e. must I do 4th year as well? Many of the good institutions such University of Law require a 2:1, others state they need a degree and that's how vague it is- so does this mean I would have to do fourth year? Note: HWU is not a British institution but a Scottish one, and I'm struggling to understand what is the Scottish equivalent of a ordinary British degree.