It is possible to dismantle the headlight and change the position of a plastic part inside but this seems like a lot of effort to go to for a holiday trip, it's different if you're exporting the car.
I just use sticky headlight converters when I go abroad.
You can get stickies that work on a B. The very cheapest ones might not but at least one mainstream type do. About £6 if I remember right. Mind you tried to get them off to reuse later and they just disintegrated How often do you plan to go.
I drive across France in my B usually 2 or maybe 3 times a year and just don't bother about the lights, my theory is that being a LHD car the cops think that the headlamps have been fitted to suit mainland Europe. Anyway, whilst the lights are adequate they are not that powerful so as to cause a problem to oncoming traffic.