It looks like you're doing a good job from your own initiative Bencrow. Here are some resources:
First, on this site there are a lot of useful members, but on stands out for his amount of quality posts - Bernhard. Do a search on discussions he's been in and you'll have a lot of good posts to read.
Websites (free):
https://www.sheetmusicarchive.net - free sheet music. Not the best editions, but FREE!
https://www.practicespot.com/home.php - ideas to use in practice
https://members.aol.com/chang8828/contents.htm - book covering many topics in piano
https://pianoeducation.org/index.html - I liked the interviews on this site
https://www.music.sc.edu/ea/keyboard/ppf/index.html - online magazine, mostly teacher oriented but I found some useful articles here.
https://www.pianoeu.com/intro.html - a confusing and difficult site, and I think part of the main premise might be based on a misunderstanding... But I still found the ideas covered in this site very useful
https://ericbarnhill.wordpress.com/ - recordings of impressive improvisations, the FAQ and improv facts to the right have useful insights
https://www.improvise.nl/cursuseng.html - a guide to improvising.
Some project gutenberg e-texts I've found, haven't gotten around to reading them all yet though:
https://www.gutenberg.org/files/18284/18284.txthttps://www.gutenberg.org/files/17474/17474.txthttps://www.gutenberg.org/files/18560/18560.txthttps://www.gutenberg.org/etext/4386https://www.gutenberg.org/files/16225/16225.txthttps://www.gutenberg.org/files/16459/16459.txthttps://www.gutenberg.org/files/15604/15604.txthttps://infomotions.com/etexts/gutenberg/dirs/1/4/3/3/14339/14339.htmhttps://www.everything2.com/index.pl?node_id=1368793 - Schumann on learning music
Books:
The Great Pianists by Harold Schonberg - An overview of the great pianists in history
The Art of Piano Playing by Heinrich Neuhaus - A bit disorganized, but covers a lot of ground
Mastery by George Leonard - Not about piano, but about learning in general. A compact book, well written, good description of the how to approach longterm learning. Highly recommended.
With Your Own Two Hands by Seymour Bernstein - Covers a lot of ground, I like his attitudes, the best description of sightreading I've come across.
Great Pianists Speak For Themselves by Elyse Mach - interviews with great pianists, interesting and inspiring. There is also a second part.
There are more, but these are what stick out off the top of my head. Lots to keep busy with! Anyways I think you're on the right path, seeking information, learning to read, getting your hands into some pieces and starting on scales. Have fun and feel free to ask any questions!