MAC forum says it only works if you are in the USA, something to do with currency etc, etc so I guess it won't work over this side of the pond.
However, this is how you can make a ring tone. Download Super C from eRightsoft, its free. This will convert any media file format into any other media file format. Convert your tune to wma format. Now download Audacity, also free, and you can edit the song to a suitable bit for the ring tone. Check for a suitable format to save it in or user Super C again to make the conversion.