To me, if hes got these rear lights, tints, and other bodywork mods, if it was me, if id had this car for 2 years, and only done such a small amount of mileage, and left it sat on my drive, id be out enjoying it, and putting at least near average mileage a year. It looks like its a relatively Young owner aswell.Those lights are shall we say "a Personal choice". R32 or Ed30 rear clusters are much more OEM look rather then very "Ebay" look.
It is possible to mess with the mileage on VCDS or Vag-com, so yes best check service history with your local dealer as they can check any warranty or service work on its Nationwide database.
Although look closely at the steering wheel for signs of wear, Seat Bolsters aswell, Heavy wear marks on the Pedals, and around door handles for signs of Nail (finger marks).
It does sound abit suss, for mods done and such little useage if hes the only keeper.
check Vin numbers and Reg plate for the obvious cloan'd car or Vin number under the bonnet being tampered with.
Just do you homework
Perhaps look at some others as there are lots out there for 15k, even a good spec Ed30 can be brought for same money your prepared to shell.
Its a Great car. You wont be disapointed.