This is an urban myth that is being put about, but it is NOT TRUE - read the actual Inspection Manual here
MOT Documentation Contents Page
See Section 1.7 where it says:
"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."
The key word is MAY, note it doesn't say MUST. So you can still pass the MOT test if you have HIDs but don't have self-levelling or washers - but if those are fitted they must work.