Why don't you use Xiaomi IR controller since you are using Xiaomi products?
Don't think can use UK 3 plug for aircon control. Socket type also different.

Came across this article on a provider's IOT outage. What's even interesting is how in the comments, one forumer, Manolo, detailed his smart home setup using Raspberry Pi running Domoticz which he connects to his smart meter by USB; receives data from personal weather station over 868MHz, switches on/off lights on 433MHz, Z-Wave usb stick connected to various sensors, Wi-Fi to receive variously placed readings from temp and humidity sensors. Cost him less than £500 to build it but of course, he took his time to learn to set it up.

Do you use any IR blasters? Which is good? I just ordered the RM Mini 3. Was also considering the Xiaomi but the RM Mini is so cheap. Probably plan to use to control Toshiba TV, UniFi Huawei STB, Deka ceiling fan and Midea AC.

No native Homekit support but that's fine.

there are another model which comes with keys for manual overwrite

but the particular model i wanted you can use 9V battery to power up the door when the inside batteries are flat

Too many info scattered around
Would like to know if I buy sonoff to replace light switches, what should I take note?
Is there any issue with having neutral or not?

No neutral, no Sonoff

then for our normal terrace house, is there neutral line?

then for our normal terrace house, is there neutral line?

then for our normal terrace house, is there neutral line?

Sifu, my sonooff switch  all blinkiing, dont know why. Delete it and do the pairings again and fail , whatthe prob , can give solution?

Guys,
I'm a bit confused with no neutral or got neutral smart switch.
If no neutral, how do you power up the smart switch? Using battery?

Everyone's house confirm got neutral line. But your switch got neutral line or not, 95% sure don't have.
Blinking because cannot connect to your router. What did u do ah? 
No neutral switch will let some current go to the load to keep the switch on, IINM.

Already switch off and off the router but still got same problem, how to solve the problem?

The Sonoff model failed to connect to your router:
The LED blinks once every 2s, and the device is offline, it means it failed to connect to your router.

There are some reasons causing this problem:

a. The WiFi strength is weak. Your router is too far away from your Sonoff model, and there may be some interference in the environment.

To solve it, please take your Sonoff close to the router. If the problem still exists, please cut off the power of Sonoff, delete the device from your account. Power it up and re-add.

b. Make sure you are not using the 5G WiFi. If you are connecting to 5G WiFi, please delete the device and re-add via 2.4G WiFi. Some WiFi Hue/Bridge may not compatible, this is rare.

c. Make sure your router settings don’t open the MAC address filter.

d. One normal router usually supports about 10-15 devices(including phone, PC, tablet, and all other devices that connects to the same router). Please make sure the number of devices currently connecting to your router doesn’t exceed its max limit.

And if possible, reserve the Sonoff IP address in the router so that every time it reconnects, it will use the same IP address.

Maybe i use a many device for aqara/mijia?

then for our normal terrace house, is there neutral line?