I'd start by reading the FAQ's, then spending oh a few days reading all the threads here...
Oil changes are like $50, or less. You do need the proper oil. [I'll let you do the reading up on the 505.01 oil controversy--head over to the Fuels and Lubricants forum for that. But I'd go with the proper 505.01 oil.] Your dealer may have some, but I typically just mail order my oil, oil filters, fuel filters, and the like.
If you just bought the car, I'd change the air filter, fuel filter, oil and oil filter, along with the cabin filter. And do a brake fluid flush. The timing belt and serpentine belt should be good until 100kmiles -- I'd replace a bit on the earlier side, just out of superstition. Like at 98k. I'd also change the tranny fluid at that point, with the VW OEM stuff (but again, go read up on it).
Oil and oil filters should go 10k. Don't bother trying to change every 3k with cheapo oil, let along gasser-rated oil. Fuel filters are supposed to be changed every 20k (but some have gone 100k!). Air filters go at least 40k, if not longer. Cabin filters, should probably just change every year. [Rumor has it, letting them go for a few years may lead to problems with the blower motor running hot, drying out the bearings, and subsequently blowing the resistor pack thermal fuse.]
I can't think of anything else that needs attention in this 80-100kmile span. Well, wheelbearings (when they make noise), struts (some think they are kaput after 40k, many get replaced once or twice within the cars lifetime), and rear brakes (they wear out faster than the fronts, just so you are aware). Maybe changing the ceramic glowplugs out for metal ones (plus the much-desired tune), and keeping an eye on the camshaft wear (which is a big issue on these PD motors--but no sense in replacing it until you have stumbling issues and/or loss of power). Lastly, word is that the BEW motors have a half-way decent DMF clutch, but it's still something that sits at the back of my mind always...
