In the good old days, you'd write your book in Word and email (or fax!) the draft to your editor, plus post off some slides to the designer, and then just sit back and wait for your book to be published, and the money roll in (or pay off your advance, or not). This way of doing things worked well until the '80s/'90s and seemed to generate enough cash for everyone to be happy and for books of all kinds to be published. But something broke in the 21st century, and now it feels as if the only way to really make a living from writing books (a living that you can bring up a family on, not just get by on, like being on the Dole), is do every single part of the process yourself, not just the writing part, but the layout and design, the illustrations, sort out the printing, the pricing, the marketing, the freebies, the social media; everything done in order to squeeze every ounce of money juice out of a book so that you can afford to write the next one. If you can pull all these things together when you see a sale on Amazon (in real time, not in 12 months), you know you've made a couple of euros from the sale, not a couple of cents.
The final step in the process is one of the most frustrating, which is making a Kindle/Epub version of your book. It can be done in multiple ways, but none are any good for a book that features lots of diagrams. And so, rather than sit back and ponder what to write next, it's straight into HTML and CSS and wrangling your content like you used to back in the dark days of Web 1.0 and the whole shit show of the 'browser wars' (your book might look great on Apple books, or an Android, but shit on a Kindle, or visa versa).
The thing I struggle with most of all in this process is I don't seem to be able to retain the knowledge needed to master all these things at once (Illustrator, Indesign, Photoshop, HTML and CSS, Epub, etc.), meaning it's a constant switching from something you've mastered (know all the short cuts), then back to a total novice (again!).
It always works out, but the real benefit is it keeps the arrogance of mastery at bay and keeps you in your place, the place it's best to be if your creativity is fueled by struggle.
May I ask what you think is a good software program to load into a Windows laptop to begin a novice writing project? I am that novice.
Couldn't you outsource those elements to a freelancer Andy, such as on Fiver or 99 Designs? I've used them before and more than affordable for the time you save.