Hi Neil
I had a go at arduino cloud about a year ago.
For price/configurability I ended up switching to Blynk. I’ve had 5 arduino MKR GSM boards function flawlessly for the past year. I think Blynk is aimed at developers, but there was enough sample code for me to get the board running .
That said, the current arduino pricing looks good.
I’ve also been using these sim cards – 1nce.com. 10 euro for 500Mb with 10 years lifespan.
Cheers
Dave