I've got an EU spec headlight unit fitted to my Gen1 thanks to Flitwick MCs ordering the wrong part after an accident. The kick-up on dipped beam is quite small, so I kept it rather than wait for a replacement. It's since passed a couple of MOTs without problems, so I wouldn't worry too much if you can't get a UK spec unit.
For info the US spec headlight unit has no kick-up on dipped beam, so would be OK.. if you could find one!