The issue with the insert repair kit is that you also need to buy a good quality non-standard sized (9.9mm) drill bit, a 7/16-20 tap set and a bottle of the red Loctite threadlock. It might be cheaper overall to get a professional shop to remove the broken bleed screw. Either by welding a nut or spark erosion. Alas these places are getting harder to find.
You haven't said which side of the car has the broken screw? You might have better luck in the wanted section if you ask for the caiiper you need in the wanted section as opposed to a pair.
I'm pretty sure that the Omega uses M8 bleed nipples though.
Fronts are M8x1.25 Part #90369391
Rears are M7x1.0 (x 41mm ?) Part #90297538