Is your car Auto, or Manual?
The Automatic uses a different Fan, and could add a bit of time to the job, there is a special fan clutch tool, however I have read that it isn't necessary, and can be substituted for a long flathead screwdriver, but I have a manual, with an electronically controlled fan, so I can't say for sure.
Red Flag on the "green" coolant leak, of course the fact that it is leaking is bad, but the fact that it is green, says that the last person to top off the coolant used the wrong coolant.
Not that this was the source of your problem, but many people including myself are vehemently against the green stuff. (Only Genuine BMW/Mini coolant) its a couple bucks more expensive to use the prescribed stuff, and a couple dollars for distilled water (only)
If one pulley went bad, you can assume the others are not far behind.
I would replace all them, to keep you from having to revisit this job prematurely.
Now, for the cooling leak....let me just ask, do you know the cars service history...specifically the cooling system?
If you're not sure, I would replace everything, except the hard pipes, and radiator, unless of course they are leaking.. unlikely that they are.
If you are well prepared: read/print the DIYs, and have tools, and all the parts...you could knock out everything cooling system, and pulleys in 4-5 hours, as a first timer on this car. Its about a 2 hour job for me.
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