Its done 6000 miles now (TDi Vrs) and I've had to put in about 2 /3rds of a litre of oil so far....

normal or not?

The diesel engine uses quiet a lot of oil in its early life. I am suprised you have not had to put more than that in. My current PD140 with just short of 90K on the clock uses about 1 litre of oil per 6K miles even now. 2/3rd of a liter is very little for a diesel engine, and well within VAG group tolerences.

Much to my amazement I have not had to top up at all yet (7500 miles), and I do check !

ditto 8k on mine, and not a drop

half a litre in 3000 miles.

Sounds fair enough to me. About in line with mine, maybe a little bit worse.

Mine is nearly on 30K and I think I must have put about 3 ltrs in total into it since Ive had it. (vRS TDi PD) All my previous VAG cars have used just as much to be honest.