Coming home lights can be coded without having a light sensor but the lights will come on during the day as well and an error will show in VCDS that it can't find a sensor.
Auto lights needs a sensor so to do a proper OEM job, as far as I am aware, if you don't have an auto-dim rear-view mirror, you need a new windscreen which has the correct fitting for the sensor and auto-dim mirror and then a new light switch. People only tend to retrofit these when they need a new windscreen. Think the last thread I looked at on this someone said the windscreen was around the £200 mark.
You may have to replace your screen soon Matt as it has a crack in it huh, hint hint, surely you have windscreen cover with your insurer without any loss of no claims & just pay an excess, if you tell the installer you have the auto lights, rain sensor & auto dimming mirror they will fit that screen, of course your mirror fell of aswell before they did the install & you will put it back on later when the sealant has dried & when they've left, again hint hint.
Yes you need new screen, a light/rain sensor, new mirror, rewiring & headlight switch, all jobs I can do/arrange.