I have a G30 and I didn't have to do anything to my stock LED lights when I took it to France recently.
They don't dazzle anyone in France if left on dipped, as per the manual.
As others have pointed out, you can change from MPH to KPH through the iDrive's setting menu.
I didn't take any "spare lamps", but like the idea of a cheap set to satisfy the police !
You need hi-viz vests for driver and passengers, but you need to keep them in the car, and not in the boot.
Another thing to watch out for is the new lower speed limits.
Since its new, I bet police will be out there enforcing it.
Here is somthing to read...
Hope you enjoy your holiday.