i was wondering if it might be the wishbones?
i had a look at the guide on replacing them but what can i do to confirm they are the problem?
i think the disks are ok as they were fine when i put them on and for some time after.
I would try to establish first whether it is the discs or the wishbones. If the wishbones are excessively worn on the rear bush, I would get a friend to walk alongside the car as you drive along slowly, and get him to watch the front wheel when you apply the brakes. If there is excessive wear, you may see the front wheel move backwards slightly on the affected side, and then return to the former position when the brakes are released. You are in effect getting hold of the wishbone checking for any side to side movement which will reveal if one or both bushes are worn.
Or if you have a friendly MOT man, especially with the 'jiggle' plates who may check them for you!
On the subject of so called warped front discs - I do recall referring to this subject in the past? Officially, there is no such thing as warped discs (it's not me that makes this statement, but specialist brake manufactures) - invariably it is a build up of friction pad material that that transfers from pad to disc when hot, especially when the pads are 'clamped' to a hot disc i.e. when sitting at traffic lights with an auto with your foot on the foot brake, which results in high spots around the disc. As the brakes are used, any individual high spots get bigger and eventually cause a kicking through the pedal, more noticeable under gentler braking. People immediately confuse this with warped discs. It can also be caused by contamination behind the hub face and rear of the disc, especially if they have had a smear of copperslip when fitted - they should be fitted clean / dry. The kicking can sometimes be resolved by a systematic process if firm brake applications - the process is quite detailed, and is also a process for bedding in brakes for more 'spirited' driving.
You may wonder why I say all this. If you google Audi RS4 brake judder, there is a wealth of information on the RS246 forum, from owners (and from myself) about the issues encountered and the technicalities from racing / brake manufacturers.
I know Omegas are a different kettle of fish from an RS4, but the basic principle is the same.
If nothing else, may provide interesting reading before you start giving the supplier of your discs both barrels.....