All their quotes include the £1250 contribution
Right fair enough, so to get the 20% off list you need a dealer discount, the loyalty discount and VW Finance contribution, rather than the dealer just giving a 20% discount off list (VW Finance contribution is not a dealer discount and as monkeyhanger has pointed out, not everyone is eligible for the loyalty discount).
Correct, the drive the deal discount is about 12% off, then you could take the 1250 deposit contribution and current owners might be able to get the £1000 on top.
It's not guaranteed that you could get the loyalty bonus on a dtd order though as their supplying dealer could struggle to supply prior to the deadline. You would need to enquire about their stance on the offer.