As I mentioned today in a different but similar thread, HID headlight conversions are NOT an MOT fail...
For MOT rules with regards to HID kits, it is actually not possible to fail a car for a HID upgrade as it states that both self levelling system must be working and headlamp wash must be working IF FITTED. If they're not installed then they can't fail it.
The tester may fail for not emitting a white light from the front but this is down to the colour output of the light so as long as you don't go too blue then this shouldn't be an issue.
This is taken from the MOT manual for anyone who may have issues with MOT fail and HID kits.
Section 1.7 - Headlamps.
"Where HID or LED dipped beam headlamps are fitted, switch on the headlamps and check the operation of any headlamp levelling and cleaning devices fitted."
Information
Vehicles equipped with High Intensity Discharge (HID) or LED dipped beam headlamps may be fitted with headlamp washers and a suspension or headlamp self levelling system.
Where such systems are fitted, they must work; however, it is accepted that it may not be possible to readily determine the functioning of self levelling systems.
In such cases, the benefit of the doubt must be given. Headlamp washers may work in conjunction with the windscreen washers (when the dipped beam headlamps are switched on) or by a separate switch.
HID lamps may be identified by: · taking a few seconds to reach full intensity · having a bluish tinge to the light · having an igniter module/inverter behind the headlamp · having ‘DCR’ marked on the headlamp lens.
Mark.