Living, and working in an area with two cross Channel ferry ports (Poole, and in the past Weymouth) I encountered a fair few of this type of collision over the years.
Usually just outside of town where there are no street lights and traffic is very light. Foreign driver suddenly encounters a set of headlights coming round a bend in the road and instinctively veers onto
their "correct" side of the road
Many UK drivers have done exactly the same just outside French channel ports.
I would never consider taking a ferry that gets me to France (or Spain) when it's dark, or nearly dark for exactly the reasons I have detailed above. I also try to avoid night time driving in Europe if at all possible.
In this scenario, with no-one (other than possibly the driver "at fault") suffering serious injuries then I would be exceedingly surprised if a prosecution results.