After doing some testing, (albeit not here in the UK!) for our use case (electric vehicle charging stations) we’ve come to the conclusion that LTE-M is the way forward for us:
https://www.v2g-evse.com/2018/09/29/what-are-the-top-iot-platform-requirements/
NL and DE are target markets for us, so in the (continuing!) absence of a UK wide LTE-M network testing across the North Sea beckons yet again!
Jim