In general, If I have a pistol with me and have to leave it in a hotel room, I use a small lock-box and cable and try to find someplace out-of-sight to attach the rig to a heavy piece of furniture. (Under the bed is often a good option.) From a practical standpoint, however, you'll be fine if you put the gun in a locked box inside a locked suitcase. Here in the US, unless you are staying at a really scum-bag place, the staff won't even think of lifting your luggage and if you lock the bag they can't / won't look into it.
The Truth will set you free, but first it will make you damn mad!
Old Scottish proverb:
If ya' cinna' drive the fooging trook, dinna buy the fooging trook!