NB-IoT Data SIM and devices

[affinite]

Id like my OpenPlotter RPi to send packets of data when my boat is unattended. Things like battery voltages, bilge switch status etc etc.
I currently do that using an on-board MiFi router and a GSM connection which works OK but Id like to reduce the traffic down to Kb rather than Mb
I'd like to setup a NB-IoT connection so I was wondering if anyone else had played with NB-IoT SIMS and devices ?
Thanks

[PaddyB]

another option would be to stick with the gsm but just send some mqtt every few minutes from node-red, then either just monitor that on a webpage or configure an IOT service. MQTT send small packets.

[affinite]

Paddy
Thanks, I already send MQTT data every 10 minutes from Greece to the UK with a simple £10 per month PAYG SIM and if Vodafone weren't going to introduce a daily roaming charge (£1 per day) from 1st Jan Id leave the setup as it is. 
Having found IoT Data SIMS with a total charge of 10 Euros for 10 years ! my interest in IoT has been sparked
Steve