Camber affects how the car reacts on anything other than a racetrack smooth tarmac, even in a straight line.
However, assuming everything not worn, a wander that is "vague", rather than a definite pull, is likely to be tyres. A definite pull in one direction on a flat road is likely to be thrust angle, poor toe, or castor. Front toe shouldn't cause a pull, though with a steering box, will cause strange effects when turning.
Note the common factor is tyres, so if you've ruled out worn components, and learn to use that machine properly - which you clearly have some way to go, as its not about just setting it green (or even to a specific set of values) - then you have to look at getting a tyre suitable for an Omega.
Now chrisgixer did try a thread some time back to find tyres that "worked" on Omegas, with his hypersensitivity to tramlining, it was biased around tyres that do go straight - the sort of tyre you could be hacking down the motorway in, and look in rear view mirror for a few seconds, without fear of changing lanes.