bravo 120 front discs the disc seems to be to big as there is a a section about 5-6 mm that the pad doesn't contact du this seems to be the only disc size listing for the 120 has any come across this

Yes.. it's normal.
As to why this is happening... Fiat decided they need the extra ~5mm for more heat absorbing capacity...or because they are simply using already available parts.

Either way... the discs should be replaced when they get max 2mm thickness wear.... the small 1mm lip won't really matter.