If you do it, make sure it's a dentist and not a home kit or one of those new "smile clinics" or whatever they're called.
The EU Commission is looking into banning them. Technically only dentists should do this but under current law, there's a loophole that means they can kind of get away with it as cosmetics. Some of the chemicals, if you search for them, are known to cause birth defects and other such nasties. Either way, heard some horror stories about people having overly sensitive teeth forever more, discolouration, roughness etc etc so just be careful