As on most model cars, the headlight (rear casing and front lens) come as 1 unit but are actually 2 units married together with not just clips or screws but also with a heat activated rubber seals - stops water ingress.
There are plenty of videos on streaming sites that show people retro fitting or amending their headlights and either used a heat-gun or baking the light in the oven in order to detach the lens from the back casing. I only seem to see successful removals but I'm sure they are plenty more failures and I personally would not try doing it - could frazzle the electricals in the head unit.
Best alternative is to either purchase a replacement from the dealer or do some proper checking before purchasing on eBay (if you want to cut costs).
Sorry, your trip to Belgium ended in a damaged headlight - hope you manage to get it sorted mate
