hi Dominic, and welcome to the community!
You can use an INA219 featherwing, docs here.
A doubler or tripler to prototype easily.
And an Argon or Boron.
If SMS is a hard requirement, you’d need to do an integration with something like Twilio or Ubidots.
If SMS is not a hard requirement and you would use an app on your phone, you can send notifications to Telegram as explained here.
(this is only my opinion, other community members may have other ideas as well)
I know there is a lot of reading to do, but once you have more questions, ask away!
Cheers,
Gustavo.