It is very likely you could convert it but the removal from the bathroom may be a problem. You can't leave cables in a wall without something to indicate where they are. And because it is a bathroom you are removing it from it may come under Part P. Without seeing the job there is a lot of guess work but may be a lot easier to leave it where it is and get another light for your bedroom.
I can see no problem. Unless it leaves something open or unsecured. Basic rules you must not be able to get at connections without the use of a key or tool and the flex must be secure. No more than 1mm holes in top or 12.5mm holes in sides and bottom. All common sense really. Have I missed something?