Tell you a funny story. I got £1150 off my 5 door DSG GTI, performance pack, leather, basic Nav, metallic paint, rear view camera.
But I could have got £1500 for sure off another dealer and I reckon I could have got free servicing thrown in on top. What happened was that I had already done the deal and then a few days later I was driving past another vw dealer with a friend and wanted to show him the mark 7 golf, so just for the heck of it I asked the dealer for a 3k discount of the GTI. He to and fro'd to his manager and eventually they agreed on £1500 off. But I didn't push them after that. I reckon I could've got another £300-£400 for sure.
Dealers are basically 'bullsh!tters' to put it simply. I called an Audi dealer asking what deals they would do on the new S3, he was like "Nothing, you just won't get a discount on a car we'll easily sell" He then went on to say "I worked at VW until recently (the exact dealer I've ordered my car with btw) and I never gave a discount on a GTI in the 9 and a half years i worked there". What utter crap! I said I just got about £1200 off without even much negotiating. He was like "Wow I can't believe it" They just talk crap.
Do not settle for anything less than £1000 for sure. And push for £1500 at least. Best thing to do is simply spec your car and work out 5-6% off it and then say I've got this much. It's nice if the car is say £31,800 and you just say I only have an even 30k mate. And say, just tell me cos I need to go to the next dealer otherwise.
Good luck!