Found a DVLA document, but it was on a JLR site so don't want to link directly to it, but if you do a Google search for "DVLA OOJ/16/046/1" you will come across it and it gives definitions of the list price.
To even further confuse it states that servicing and warranty are excluded from the list price when calculating the 40k threshold. So if you had added in the 2 service option (£299 or something like that), although just checking the New Golf and it doesn't give that option anymore in the configurators or I missed it, then that needs to be deducted as well.
So in summary as we have all surmised the list price is minus registration and first years road tax, and now minus servicing and warranty addons.
So on GTI with standard paint & no options, currently priced at £38,900, P11D £38,165, you have £1,835 to play with, or to allow for price increases, etc.