Hi
There is often a small RCD and MCB ("fuse") box which is separate from the 12 volt electrics. Look for something about a 6 inch cube in size and usually white or grey plastic Popular mounting places are in lockers under the beds, in the back of a wardrobe etc. Usually not far from the mains hookup connector on the outside of the vehicle. They have to be accessible, but it's not something you need to get to very often.