I would like remote on/off control for two heating zones and hot water. There are many more or less smart thermostats which can do this, however they require internet access. The trouble is my phone is my wireless router - if I leave the house, so does the internet connection.
Alternatively there are a few thermostats with GSM radios [like this one](http://www.climote.ie/climote-text-message-commands/), but with more limited functionality/channels or they come with locked SIM modules and poor value subscriptions.

So as I have some programming skills, I thought about setting one up myself using a normal thermostat and having my own thing as an on/off override switch, perhaps between the thermostat and heating devices.

[This option](https://www.emnify.com/2015/06/18/how-to-fit-a-raspberry-pi-with-mobile-connectivity/) looks fairly simple, and if it all goes wrong, I can probably use the "wingle" on its own. That being said, I might not need an integrated WiFi router for this purpose!

So what I really want to ask: What embedded or mini-computer board and SIM module would make sense for a beginner with programming experience (beginner meaning the integration of the two should not be too hard)?

I suspect a Raspberry or similar thing might be an idea because of the luxury of the screen output making debugging easier? 

Second priorities would be low standby power and lowish cost. Thank you.