Hi there, you can fit them after market and there are some out there on ebay BUT... Remember that in order to be MOT legal they should also have Headlight washers and self levelling system.
Currently the MOT states that if those systems are fitted they must work but it doesn't actually say that they MUST be fitted although many MOT centres would fail if they were not fitted.
This is what the MOT guidelines for MOT inspectors currently states:-
"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" What is interesting to note is that the N.Ireland MOT states :- Vehicles equipped with High Intensity Discharge (HID) or LED dipped beam headlamps must be fitted with headlamp washers and a suspension or headlamp self levelling system
so in N.Ireland it would definitely fail.
Some good reading on the subject is here. http://www.autoexpress.co.uk/car-news/consumer-news/35636/watchdog-unfair-mot-failures