Help with supplying 3.3v to ESP and temperature/humidity sensor
I am in the same boat.  At 69 I decided a few months ago I wanted to learn electronics and boy with all my medication slowing my brain, learning is hard. I was an electrician most of my working life but always wanted to get more involved.  I too chose the Arduino way to start off and some things worked easily. For one of my projects, I am attempting to build a wireless weather station with LCD at the indoor end myself using more or less the same as you are.

As for powering a UNO away from my computer I tend to use a 9v PP3 type battery and for that from Ebay, I purchased 5 leads that clip to my battery then into the UNO.  I also purchased 5 more with soldered + &amp; - ends and I soldered the ends to an AMS1117, 800 ma, 3.3v regulator, to ensure I had stable 3.3v.  You could use an Arduino 3.3v Pro mini for your project as well.
I don't know much yet, but I do know that works for me.  

Hope it helps.

Petyoung