A colleague on the ASN-8V (new A3) forum has come across something that may also work with the Golf Mk7. It is a very simple way to make all the 12v sockets (cigarette lighter and boot sockets) stay live even when the ignition is turned off. This situation was the normal setting on all previous A3s but the the new 8V model it was changed so that they were only live with the ignition on. A bit of a pain if you want, for example, to use a power pump for the tyres.
To make the change you just need access to the main fuse box behind the glove box. (picture from the Fitting a 3-4 way cigy adapter thread by RikWebb - thanks)

In the bottom right-hand corner above the relay labelled 645 in the picture is a Yellow 20amp fuse between a Green 30amp and a Black 1amp and Red 40amp. These fuse has in fact three slots for the two blades can go into. If it is in the the bottom and centre slots the 12v sockets only work when the ignition is on. If the fuse is moved so that the blades are put in the centre and top slots the sockets should be permanently live. This works on the A3 and I assume it will work the same on the Golf 7. Perhaps someone with a Golf 7 would like to try it.