This is the responsibility of the Disability Services at your college. They should be able to provide your textbooks in an accessible format and teach you how to access them, it is very literally their job description. They need to be the first people to hear about it if you run into accessibility issues related to your classwork.

If you're working with your disability services, they'll most likely give you books that are accessible. If not, you can ask them to make it into an accessible format: most of them have the ability to do that with a scanner.

If you already have a screen reader, and your textbooks are in pdf or epub without drm, or DOCX files, recommend QRead. It's I believe 30 dollars, and has page navigation, which is important for textbooks.

Ask if they can send them as rich text format files. You can use the Read Aloud feature on Microsoft Word to read the chapters

Will you be using a phone, tablet, computer?

They each have different software you use. If you're on a p.c. you can use a screen reader for the visually impaired called jaws. If you're going to be using an android phone or tablet you can use something like moon reader pro. The Pro version has text to speech so it reads your ebooks. I've tried it before and it works well. I believe the app is 7 dollars and the free version sadly doesn't have the text to speech option enabled. I think Iphone also has moon reader on the app store. And its a very customizable app.

Not all ebooks are compatible with screen readers. You’ll need to check the publisher’s website (or ask the DS department to do it) to find out.

Also ebooks may or may not have alt text for images and formulae.

Impossible to say without more information. Where are the ebooks coming from? Kindle? Nook? that kind of thing.

As for TTS readers, I think you either mean screenreaders, in which case I invite you to google NVDA and JAWS screenreaders, or some magnification software like ZoomText or Supernova, although those two are quite expensive and need to probably be paid for by the state or some other fund.