IN the UK you will need the no neutral version of switches as you will have no neutral wire in wall socket (normally) . These come in single and double switches . Check carefully before ordering as they also have switches with neutral wire as well.
https://uk.gearbest.com/alarm-systems/pp_610096.html?wid=1433363
There is also a wireless version which looks identical but does not connect to the mains supply but uses a button battery
https://uk.gearbest.com/alarm-systems/pp_610095.html?wid=1433363
Delivery is a lottery. I have had a number of orders with Gearbest some have taken 2 weeks other 2 months. I tried to speed up delivery and used a known carrier . Delivery was quicker but they charged me VAT on delivery.
Xiaomi switches only support on and off. no dimming. Combining smart switches and smart bulbs is difficult as when you remove power with the switch the smart bulbs are off so they lose connection with the hub or wifi.
One option is to replace the wired switch and bypass the switch making a permanent on . Use the wireless switch as blanking plate and control the smart bulbs directly from HA . See above not a fan of this solution as it will fail, also leaving the circuit permanently on feels unsafe. Also there is a tiny lag when pressing the switch , a bit like when lip sync is slightly out on Netflix , you notice its not physical.
I use smart switches with smart bulbs , if HA or in my case the Xiaomi hub or Tradfri hub fail , the switch is still physical and will turn power off and on regardless the state of any home automation . The bulbs will turn off and on
The problem is when the power is turned off and on on smart bulbs they will not react to any commands from HA until they re-sync . This is a real issue , I have sensors which determine if the light bulbs are in sync and will delay commends to change the state of the lights until they are ready. see
Hope that helps