I've got a 53 plate TDCi of a friend who replaced a cracked screen b4 selling it to me, and that was replaced with a heated one but like yours it doesn't have the buttons etc - spoke to my local garage about getting it connected but found it would be uneconomical to get it done (financially speaking).
He told me something about it apparently involving re-progamming of the ECU due to the amount of drain put on the system when using the heated screen, and that, unlike some wiring circuit, the wiring for the heated screen would only be there if it was meant to have a heated screen from new - think he said there was 2 or 3 "standard" looms and that the one with the heated screen system would only have been fitted if the heated screen was fitted from the factory (not sure I've remembered all the details correctly(!) but the general idea was that it would cost more than it was worth).
Don't know if it will be any different on your newer model - maybe worth contacting an auto-electrician just to get an idea of prices (but an ice scraper & can of de-icer will be alot cheaper!!