Well, there are only four brakes on your car, so that's a good start.
IF its a binding brake causing your issues, as it's pulling left its likely to be one of the left sided brakes. Just after a drive, a badly binding brake should be significantly hotter than its opposite number, so that's a clue.
It is a DIY job, even if you fit new callipers, but you need to know what you're doing. I'd suggest you take it to a good garage, not a place that offers 'free' brake checks... Buy cheap, buy twice is the rule of thumb here.
You could spend hundreds of pounds throwing parts at your car, but it's a frustrating waste of money unless you've done some digging about as to the root causes so that you can be sure your money will have a good chance of fixing it.
To be honest, me and others have tried to help you as much as we can, but the problem you describe seems to be either not all that clear or changes all the time. It's likely you have more than one thing going on here, and possibly unrelated. I'm deeply worried that these 4 wheel alignment checks you keep having are being carried out by idiots, as logically a wheel camber that far out will show on a system being operated by somebody that knows what they're doing. if they aren't idiots, and the camber is green, then how do you know it's a problem?
Basically, you seem to listen to all the advice that says 'change this' or 'change that' but I don't have any confidence that you've gone to a good alignment specialist who for £70-100 should pin point the problem and save you time and money going forward.
Shimming to mask a problem is the start of the madness to be honest, and that's before you consider the safety aspects.
You may well be on a tight budget, but you need to sort the basics out before remaps/turbo upgrades/coil overs etc.
Cars will pull to the left hands off from a start, especially torquey front wheel drive ones. All A3's/S3's will have the rear wheels pointing in more at the top when they've been lowered and haven't had other components changed to eradicate it. If one wheel points in at the top and one doesn't, what does that tell you? It could just be a collapsed rear suspension rubber, but until you or somebody who knows what they're doing checks it, you could go on chucking money at red herrings...
I think this is the second time I've said something along these lines, but really, there is only so much help people can give to a vague/changing description of the issues, and without actually seeing the car.
I know it's irritating when your pride and joy has a problem, but in my humble opinion you need to take a step back and get to the root causes. If you can't do it, then find a garage/specialist who can.
I know you may be tempted to latch onto the next person who says 'change this mate, it was the problem on mine', but think carefully before you do.
I hope you get it sorted mate, I do, but remember a lot of people on here are experienced with these cars, and best of all give you their time/knowledge for free. Meet them half way by at least trying to be consistent with the issues you're having, and getting expert help when they suggest you should. It's difficult sometimes for people to keep track of what the history is with multiple threads all describing related matters, maybe try to keep it in one place so that folks can see the history and what you've tried already?
Again, good luck!
