I had two problems with headlamps. The first was that the metal cowls that held the bulb in place were completely rusted through. The second was that no amount of sticking things to the US lamp would divert the beam to the left. It failed the MOT on both counts.
Luckily I discovered (due to the power of globalization) that International School buses use exactly plug compatible headlamps as a Daithatsu Fourtrack - which you can buy on eBay with a UK left side beam.