It’s not about any mentor, it’s about finding the right resources, whether that is a literary agent to assist in the publishing process or a step-by-step guide for self-publishing.
It’s definitely up to you to figure out where you need help, and luckily there are a TON of resources online these days!
And don’t forget — self-publishing does NOT preclude you from being traditionally published. In fact, if your self-published book does well and gets good reviews, that is a sign to trade publishers that it could sell well — and they have a lot less work to do on it. That happened for me!
Good luck with your book, I can’t wait to read it!
P.S. For me, the hardest part of writing any book is not starting or the actual writing — it’s knowing when it’s finished. When to stop adding more and more information or sharing “just one more thing!” As an expert in your field, you have a lot of knowledge and it’s impossible to cram everything into just one book!