They're luxury cars so if anything goes wrong you pay more than you would versus a non-luxury brand. Do they break often? That depends on you and the previous owner. The engine bays get hot since they're turbos so your rubber vac lines and plastic check valves are eventually going to crack. Do you need to go to the dealer? If you're clueless, then sure. If you like cars you get OEM parts from places like genuineaudiparts or germanautoparts and DIY. Other things like brakes and such are like any other car. The big things with our design is making sure you always use synthetic oil with an oversized filter to avoid sludge issues.

I bought my car in 2005 as a certified used A4. Since then, I've put on new tires, and always had Audi chagne my oil so if I do get sludge I can easily show the oil was done on time and properly. As far as DIY, I've done my timing belt early (plastic impeller on water pump can cause belt failure and blown engine, do early with new metal impeller water pump), did my own brakes, done the engine coolant temperature sensor and rear coolant flange. I've done the performance stuff below.

I love my car and tell people all the time how I'm an Audi lifer. I wouldn't recommend it to a single mother because she'd pay through the nose to get things done at the dealer but otherwise, it's great. Since the car is listed in gbp, you're in Europe and I would think dealer work might even be slightly cheaper for you?