Well I've phoned around a few BMW dealers and nobody, so far, really knows. One said that I need a sticker kit, one said that there's a lever (although couldn't tell me exactly where the lever is but suggested I read the manual), and one said I need to take it into the workshop to get it done.
The 'workshop' solution I find a little strange as that would potentially mean that I would be driving in the UK with a non UK compliant beam pattern until I obviously went abroad.
