Legal in USA as well, Europe is slow to take up new technology as usual, maybe in UK we can get them made legal after 2019 when we have left the technological backwater..
Oh, no, I don't think so..
This kind of led lamps cannot be legal because of their geometry: halogen reflectors are made considering the position and thickness of the tungsten coils, and led lamps cannot replicate this two parameters; we will be allowed to use led lamps only when LED will replicate the geometry of an halogen one, and I think it's a good thing: we need better brightness, but also less glaring.
Anyway, ECE are the best regulations in the world concerning lighting car equipment: americans envy us our projectors because we have better light distribution, less glaring, more performance (adaptive matrix here are allowed); state of the art lighting technologies come from european and japanese brands (AL, Hella, OSRAM, Philips, Koito, Stanley), so I think (for headlights) you'd better to keep following european rules...