The problem is that Netlify does too much of the work for me, which means I'll still be relying on someone else's service to create the new site. If I'm going to take control, I need to take control properly. I'm taking Willem's advice and I'm going to roll my own.
There's going to be a big learning curve here. I'm going to need to learn about Hugo and its templating system; deal with GitHub pages; establish a workflow that can post based on Markdown files from my computer as well as from my mobile devices.
I use Editorial for text files when mobile. There are workflows available to do all of this, but it's going to take a lot of configuring.
At the same time, I have to play around with the design of the site, look at how I'm going to make the best use of CSS grid and work out how to implement it all.