A franchised dealership is probably going to take ossue with you providing the oil for an oil change you want them to do. Oil unit prices were reasonable last time I paid for a service myself, at about £11/L. There's 5.7L capacity in the 2.0TSI/TDI engines.
I'd agree with the above that the oil change is easy, but unless you're doing additional changes (e.g. halfway between services if you opted for long life regime) to the official ones, I would get them done at a VAT registered garage using OEM oil filter, sump plug and the correct VW oil spec to retain your warranty.
So, I had the oil change service done today. My VW dealer said happy for me to provide oil next time as long as in a sealed bottle, VW Longlife 3 logo'd and one that complied with 504/507. They charged £112 inc VAT for 6 litres of oil today. On Ebay 5 litres £44 delivered, so probably £60 for 6 litres.
I have no issue with the other parts, ie OEM filter, plug, etc, as they're normally reasonably priced, just the oil.
I was pleasantly surprised that their labour charge was only £33 + VAT. I thought dealer's labour charges were normally ramped well up!
McLaren were also happy for me to supply the oil, as they were going to charge me £275 it. I supplied it to their spec (Mobil 1) for £75. It's just a principle for me. IMO, Dealers would be thought better of, if for those in the know, their charges would be seen as reasonable.