Many people have never encountered the term "Motorhome Habitation Service" before, also called a habitation test.
Just think of a motorhome habitation service as being the motorhome equivalent of an MOT. We help check and maintain the functionality of all aspects of your motorhome that are used for living such as, LPG, water and electricity. These items can be a safety issue if not checked periodically, and may also render your warranty invalid if not checked. Especially, if the manufacturer has a list on the warranty which, has a habitation service stipulated to be tested annually to ensure conditions are met.
The actual service isn't mandatory in a legal fashion (at the moment) but, it would be foolhardy to drive around in a motorhome or campervan that doesn't have its annual habitation service; due to the number of issues that could arise unchecked if not inspected.
Electrical safety issues could arise which could prove dangerous, LPG leaks could occur that could prove dangerous (if not fatal), and water leaks could happen that could prove very expensive. So, you can see it's well worth the peace of mind if nothing else, to pay out annually for a check to detect or prevent any issues.
A common thought process is that "I don't use my motorhome or caravan very often so, it's not worth paying for the test", this isn't the case as the lack of use itself can cause issues too.