It is well known that the VW engine plant manufactured an early batch of T5 180bhp BiTurbo engines which had a new design of EGR cooler. This was made of aluminium which corroded internally and caused wear in the cylinders which in turn increased the oil consumption drastically. These engines were manufactured from 2010-2011. Following that, the EGR was modified a number of times, eventually with a special coating inside which prevented this corrosion.
My 2010 van suffered from this issue resulting in a new engine eventually having to be fitted. Since then it hasn't used any oil so the EGR problem has been resolved.
As your van is 2012, it should have been fitted originally with an improved EGR Cooler (probably 'A' suffix) which, from your description, has subsequently been replaced with presumably the latest 'D' suffix model.
It is slightly worrying that the MOT test spotted a lack of oil on the dipstick as while back, but since the van has traveled 40k miles since then and been serviced by a VW dealer I should think there shouldn't be any serious issues to worry about.
Alan