I've recently been down this road. When looking for a way to automate my lights, at first I was going to go for a sonoff touch WiFi switch. I like sonoff because their stuff is well made and easily hackable which enables you to flash your own firmware to add mqtt support etc
Luckily before I placed the order I noticed that the sonoff touch also requires a neutral at the switch so that was a non-starter for me in the UK. I then actually did order one of the sonoff basic power switches, wired this into the lighting circuit above one of my lights and pushed it into the void between the joists above. This solution really did work well so I planned to roll this out everywhere..but then found that it simply wasn't possible with some of my lights in some rooms due to lack of space in the void above the light fitting.
So this led me to start looking at switches again and in the end I ordered a bunch of Byron / Home Easy HE107 and HE108 433mhz light switches on ebay because I knew there was a good chance I'd be able to reverse engineer the 433 signal / home easy protocol. This plan worked too, they look ok and I've now got them controllable via WiFi with an ESP8266 433mhz bridging widget that I built. Please note that the Home Easy stuff is now discontinued / no longer being made but there's still plenty of it around to be had.
It's all a bit of a faff to be honest and something tells me that it's only a matter of time before something like the sonoff touch becomes available without requiring a neutral wire..perhaps it already exists? If not it seems as though it should be possible to create a device like this because if Byron can build a 433mhz controllable switch with no neutral wire then I see no reason why some other manufacturer can't build a WiFi controllable switch with no neutral wire.