Excellent choice, I've got the 2.0 TDI.
It's the first deisel I've had (apart from the wife's car), the last engine I had was the 1.8 20v petrol turbo which was lovely and smooth, quick and refined and I was really worried that I would miss the performance, but not at all.
The torque of the 2.0 TDi is immense (same value as the 3.2 V6 petrol @ 320nm). Off the lights, from a standing start its not that quick (you run out of revs in first gear), but when on the go, the in-gear times are stunning, and I am sure my 2.0 TDI sportback is a quicker point to point car than my old VW 1.8T 20v.
Not that I care too much as it is a company car, but the fuel consumption is amazingly low too. (as you say good low CO2 emmissions)
The only thing to watch is the oil consumption, you have to use Audi approved oil to remain on the variable service intervals and that is £12 per litre
, when you get the car there is a litre of the stuff in a little soft case in the boot tho. I've done approx 7000 miles and have used 2 litres of the stuff.
In summary, you won't regret, its a cracking car and stunning diesel engine, enjoy
Sheks