Reddit mentions of Critique of Pure Reason: Unified Edition (with all variants from the 1781 and 1787 editions) (Hackett Classics)

I would say yes, but with a few caveats. I myself am a bit of an autodidact, and I study philosophy as a hobby in my free time. I am currently a university student who works part time, so I sympathize with your concerns about limited time and energy. Some things I think you should be aware of:

• Studying on your own will be slower and generally less efficient than getting a degree. You won’t have the same obligations or motivators that university students have.

• You will lack access to resources that university students have. This includes both academic material (journals, essays, books) but also an environment with instructors and fellow students to consult when you’re confused.

• You will not have the benefit of writing essays and having them graded by an instructor.

Despite this, I still think there is a lot to be gained from self study. You have the freedom to pursue whatever you want, and you can go at a pace that’s comfortable to you. Plus there’s something to be said about challenging yourself and doing constructive things in your free time.

It may be best to start with introductory texts like Copleston’s history to get a general idea for each philosopher and to find what interests you. If you are still interested in the thinkers you mentioned, you should move on to primary sources. I’d recommend the following reading plan which should cover some of the “essentials” and has a sort of progression from one thinker to the next:

1. Readings in Ancient Greek Philosophy: From Thales to Aristotle
   
2. Descartes: Selected Philosophical Writings by Descartes
   
3. Enquiries Concerning Human Understanding and Concerning the Principles of Morals by Hume
   
4. Critique of Pure Reason by Kant
   
   These four books will give you a solid foundation in western philosophy. You have the fundamental ideas and questions from the Pre-Socratics, Plato, and Aristotle, rationalism from Descartes, empiricism from Hume, and the synthesis of the two in Kant. Moving on:
   
   
5. Logical Investigations by Husserl
   
   
6. Being and Time by Heidegger
   
   
7. Being and Nothingness by Sartre
   
   These three cover your interests in phenomenology, from its foundations in Husserl, to Heidegger’s magnum opus, to Sartre’s interpretation and his development of existentialism. Finally we have:
   
   
8. Dialectic of Enlightenment by Horkheimer & Adorno
   
   
9. Speech and Phenomenon by Derrida
   
   These two cover Horkheimer & Adorno’s critical take on enlightenment rationality and Derrida’s deconstruction of Husserlian phenomenology.
   
   None of these books are particularly easy (especially Husserl and Heidegger), but I encourage you to try! Take it one book at a time, read slow and take notes, and consult the IEP and SEP if you’re confused, watch YouTube lectures, or ask on this subreddit.
   
   Good luck!

For Kant's Critique of Pure Reason, Kemp Smith and Guyer/Wood are both good options, but I would recommend the Pluhar translation.

If you want to try to read the Critique, you should first read Kant's Prolegomena to Any Future Metaphysics. He wrote it to introduce the project of the Critique, and it does an excellent job at this. It's available in the Cambridge collection edition as part of Theoretical Philosophy After 1781 or on its own.

Secondary literature would also be a good idea. The best reference is Allison's Kant's Transcendental Idealism. Allison interprets Kant a very specific way on a number of contentious issues. For excellent references which adopt some alternate views, see Guyer's Kant and Kant and the Claims of Knowledge. All of these would be excellent secondary references and of great help in approaching the Critique. Guyer's Kant is probably the easiest read, so might be a good place to start.

For Descartes, you should get the first two volumes of the Cottingham edition called The Philosophical Writings of Descartes. The Discourse is an excellent place to start. With it you should also read The World and at least some of the Rules for the Direction of the Mind; perhaps the first six or so, or more if you find them interesting. These are all in the first volume. After these, you should read his Meditations, which are in volume two.