Woo, where to start, firstly to the op.
I've been there on my first omega, didn't know about oof then. Bought from Dk motors in thatchem, it needed a front shock as it was leaking oil, except they made no attempt set the camber, giving similar results to your picture. I was alerted to mine by the wire "tinging" off the bottom of the suspension cup. If left it would definitely have blown out.
.....And unfortunately it's probably not been helped by general poor omega knowledge in the motor trade. Cheap wishbones don't last as a rule, although there are some here with reliable ones fitted, still a gamble not worth taking IMO, unless the owner is experienced enough with this car to recognise the signs of problems approaching. lemforder are the way go go for wishbones, torque the bolts correctly with wheels loaded. Do any other steering or suspension work while your there, and set the camber to 1degree.10mins as "wheels in motion" recommends. Whoever set the camber on yours may as well not have bothered, in fact if it was me I would take that tyre back and show him

it could have killed you and others. Failed wishbone bushes or not, clearly the camber and toe are way out. As are the factory setting btw.
If it was me I would leave the spare on the car until you can rectify the faults and get it set correctly asap. Otherwise the new tyres will ware similarly and will pull for the rest of their life on the car, even when set correctly later on.
Re pro tyre, if they are part of the same Micheldever franchise as pro tyre in Slough, avoid IMO. Micheldever tyres do give good results, but certainly have failed to pass that info on to their other branches.
Squealing tyres is not always a car set up issue imo, just as likely completely worn out and polished tar mac, ESP in local car parks such as our local waitrose, every single car pulling in squeals turning in.
However if it does it does it on numerous corners, beware.
Wow, what a mare.