Thats an age old debate, the wording in the UK is in reference to if you have them, they must work. On my old mk2.5 i retrofitted the washers because why not but i didnt bother with the levelling, never had a problem. I also had a chat with the MOT guy about it and he said its completely unworkable, the guide is not clear, you could for example, rig up a couple of 3mm tube down the side of the car with a squeezy bottle pump inside, job done, washers enabled. you can get cheap ***** leveling from china that will move the lights depending on angle, no its not the fast movement a proper solution would have but that isnt what is asked for, its there and its working, job done. Not to mention many places have no means of testing these anyway!
that being said, i dont think i would bother, the performance benefit doesn't add up to the cost of even the lights, let alone anything else.