[missjellyfish]

Write first, layout second.

Layouting is an entirely different job than writing. For long and very long textual content, I have yet to find automated results that give me control and look professional [0].

If you want to stay FOSS, learn Scribus. Becoming decent at typography and layouting is a bit of a journey, but I found it to be not too bad. If spending some money is okay, I'd go for Affinity Publisher.

None of those tools can do ePub. ePub is a format I've grown to hate; my pipeline currently consists of custom python -> pandoc -> custom python -> manual fixing.

For writing, don't worry too much. Use a program that you're familiar with and know how to use. If you don't write fiction with highly complex custom worldbuilding, a normal word processor is probably fine. I personally write urban fantasy novels, and I use a combination of Word and OneNote to manage everything as long as I am in the writing phase. It's more important to be easily able to change the layout than to have it finalized. For example, I like proof reading on Normseiten (A4, 30 Lines per page, less than 60 characters per line, monospaced font - I use Comic Mono) which is distinct from my usual writing format (Adobe Garamond, 12cm by 19cm pages with uniform 1.5cm borders).

> What are my options in terms of self-publishing?

Depends on the subject matter. If you're writing is any good, might as well try and score a distribution deal (at which point most of the layouting things will be out of your hands anyway).

All the best for your book project.

[0]: LaTeX sure looks nice, but gives me no control at all.