markjay said:
A complete retrofit will require also the suspension height sensor and headlamp washer system
MOT guidelines state when Xenons/HID's are fitted, washer jets and levelling system must work IF in place. Should the car come with them from factory, they must work. If the car originally doesn't (in the OP's case) these are not needed for the MOT
With regards to the light temperature, I can't remember the cut off point of 'legal' but the MOT tester cannot remove and check a bulb for its colour temperature etc, so if you get away with something really high then fair play... I believe the police can't check on the roadside either but can give an order to have them checked
All this provided they are within projector based headlamp units aligned correctly, with the correct RHD drop off on the drivers side low beam. Meaning shoving a HID kit into a bog standard reflector headlamp is highly illegal causing glare and the wrong spread. Although I've seen countless people with even drop offs
Also they need to be manually levelled, i.e from within the car. Some kits don't have the motors built in but most will take the cars previous motors from the original headlamps to suffice
There shouldn't be a pause between the switch from low beam to high, and the low beam should remain constant on during times when the high beam is on etc etc
Everyone always gets worried about the washer jets and levelling sensors when they don't need to

me included before I looked properly into it on a previous car and it is perfectly legal