Thanks for the swift answer dclaar.
I completely ignored the Remote section as it had blocks referring to sliders and buttons. I should have realized!
I have gotten that working without any problem. However from what I can see it uses the M5Stack WEB site to create a small WEB server or at least redirect traffic which would be fine for most applications.
However, what I need is to be able to send something using POST from my PC on my local network. (It could be JSON or plain text). My M5StickC already has a fixed IP.
I don't think any of the options you suggest will do what I need in Blockly, so am I stuck with moving to python, or do you have any more suggestions!