I've just had my cooper 2003 back windows tinted & it just looks crap,the guy has trimmed the tint around the spotted edge of the window & told me that's what he had to do because it won't stick over the spotted edge??

Is this the case for minis that had a tint as standard?

I've never heard this before. I've had plenty of different tint jobs on various vehicles that have went right over the spotted edge lines of the window. Never had any issues with it bubbling or anything. I would say your tint guy is incorrect.