@Jupiter01 it may help if you also say how high your ceiling is from the floor. Whether the room is fully furnished or sparsely furnished. Are there any draughts around the doors/windows. Do you have double glazing/heavy curtains. Is the floor tiled/carpeted/bare boards/bare concrete. Is it a ground floor room or top of the house, (in which case does it have a cellar if ground or good loft insulation if top of the house).
Nobody can give you full advice on what type/size of heater without knowing all the details, (or at least as many as possible).
Nobody can give you full advice on what type/size of heater without knowing all the details, (or at least as many as possible).