Am only looking at doing a post grad diploma or certificate at my local university (Glos uni). I will graduate Jan 2005 with hopefully a 2:2 in bus admin Without speaking to the course bosses, and charming the hell outta them, does anyone know what are that chances of me getting on a course of this caliber with this class of degree?

Just apply, see what happens. As I mentioned in another thread, I know a person who got into a graduate course at Oxford with a 3rd. There are no absolute rules in most places; it depends on factors like who else is applying for the course that year.