Sort of. You can only have what’s known as a “reduced weekly rest” in a truck (more than 24 hours rest, but less than 45 hours in between weekly shifts). However, this must be at an established truck stop or service station with facilities. Not an industrial estate, or layby. The maths can get deep, but usually a driver can have one reduced rest every 2-3 weeks.
A “full” weekly rest has to be more than 45 hours between weekly shifts. You cannot spend a full weekly rest in your truck, full stop. So you’re correct, your boss has to fork out for a hotel if you’re having a full rest.
This rule has mainly come into play as a way of combating Eastern & Southern European hauliers sending their trucks and drivers into Western Europe to work for months on end (particularly Romanian and Bulgarian, who provide the cheapest haulage in Europe). In doing so they are undercutting native hauliers, and subjecting their drivers to quite grim living conditions (sleeping in a truck for months on end in industrial estates and laybys, with no access to toilets and showers. As well as being paid exceptionally low rates, but needing to survive in very expensive countries. “Social Dumping” I believe it’s called).
This rule hits these hauliers in the pocket, and makes it much more complicated and expensive for them to do the above practice.