Quick Q. Do all Z's have headlight washers? Did they come part of an 'extras pack'? Do only Z's with Xenons have washers or are they also on Z's without Xenons?
Mostly correct, but not an MOT fail. The MOT requirements are that the washers and self levellers, if fitted, are working. If they are not fitted, they can't be tested and so can't be a fail.
Legally you do need self levellers and washers (it just won't affect your MOT)