Teeth whitening is a technique used by Dentists to make teeth white by reducing the yellow stain. This can be done either by laser or non-laser method. Under the Laser method, laser and a high power light source is pointed on the teeth. This type is recommended only for severe case.
For a mild one caused by smoking, drinking tea, coffee or wine, the non-laser method is sufficient. If you are from Leeds, you can approach any of the Leeds dentists and take their opinion to know, if your problem is severe or not, to opt for the laser method.