Today I managed to reflash a Sonoff S26 UK version plug with the Tasmota firmware, and it is working perfectly ( so far!) with the gateway with the Tasmota Addon from @t1m1
Flashing the plug did involve soldering on wires but using the new Tasmotizer program it was easy to backup & flash it.
https://templates.blakadder.com/sonoff_S26.html
So that is now two “cheap” plugs I have got working 
Thanks to all the shoulders I have been standing on!