Well, I've gotten an answer from Wood BMW in Salisbury (thanks Nigel!). There is a switch on the '11 335i Adaptive Xenons, but it requires that the front wheels, arch insulation be taken off on order to access it. At least I won't have to spend £2000 to pass a MOT!
On a similar note, the euro headlight switch will enable the rear fog lights as well (not originally available on Canadian spec!) with no coding required.
2011 E90 335i - Deep Sea Blue|Black Dakota|Brushed Aluminum|Nav|Apps|Steptronic|287 Wheels|M Sport Suspension|Model Designation Deletion|Canadian Spec
Ordered 18 May 2011|Production Week 22|Completed 1 Jun 11|Arrived 8 Jul 11!!!