Wrong, MOT states:
A car with HID lights MAY also have headlight washers and self levelling which must be checked and in working order if fitted.
You'll only fail if your car came with washers and levelling and they are no longer working.
If you are thinking to go HID I recommend you search morimoto h1. TRS sell them and if you're willing to bake your headlights open they are a really easy to fit, and will give a brilliant Bi-xenon beam! No cutting or modding involved!