Need a bit more info.
At what speed, when braking?
I've had both, mine wobbled at higher speeds, solved with new tyres and balance.
Then last year they wobbled under braking, solved with new discs and pads.
Mick 
It's a case of trial and error. Going on your info, it's hard to tell on a forum.
My own case, most would say a "W" plate Omega and still got original wishbones, tis true

Most by this age would have had replacements.
When I bought my estate it had wheel wobble at low then higher speeds, so I had them balanced. A great improvement but still there. Put up with it until a rear tyre looked a bit near to the legal limit, the rest were ok with good amount of tread left, but one with uneven wear. So I had the lot replaced, and wheel wobble vanished, drives straight and true at any speed.
Not saying it's the above and only that's your problem but yes it could be tyres, wishbones, steering idler etc.
I've now got a saloon and that tramlines a good deal so me thinks will look at the steering idler first, as that is the cheaper option to deduct from a list of possibilites. All the tyres are newish, but at over poss £60+ a corner will look elswhere first.
Mick