Retro Fitting Light Switches - What is available in the UK

You can’t order anything from the US because the Z wave frequencies are different from UK and they won’t be able to talk to the U.K. Version of the SmartThings hub.

As far as what’s available in the UK, as long as you have a neutral at the switchbox, there are a number of zwave options. Vesternet has a very good selection.

If you don’t have a neutral at the switchbox, see the FAQ for UK lighting, it covers about a dozen different options in detail: