i don't want to discourage you but you should know there's an important difference in studying biology and other fields. think of it as a comparison between biology and something like cs; you can be an expert software engineer without knowing anything about networking or graphics, or an expert data scientist without knowing about crypto or hardware architecture. the beauty of cs is that with relatively little base knowledge, you can dive into a discipline and learn without too much fuss, given that other elements from other disciplines are either irrelevant or abstracted away. fundamentally you can still approach biology the same way, but the base level of knowledge you'd need is a lot greater; at the very least you'd need a reasonable grapple on (organic) chemistry, histology, cell ultrastructure, physiology, biochemistry, and (lots of) metabolism (and in most cases genetics/genomics and immunology as well) before you'd be able to tackle those disciplines.
having said this, it's definitely still accessible in terms of learning curve, and a solid outline of the important stuff is enough to get by with most areas of biology if you're just passing through (pic related, obviously no single person is going to be acquainted with every human metabolic pathway); the only thing to be wary of is the quantity of material. another thing is that, in contrast to something like cs where you often learn something by doing it yourself, there's obviously none of that in biology (except for applications like PCR and gel electrophoresis, still pretty niche), so if you rely on that style of learning to avoid absorbing knowledge by poring over text you may have a harder time here.
in terms of recommendations i'd start with a high-school textbook and make sure you're alright with the breadth in that, then move onto something substantial. stay away from uni textbooks, the detail is overkill especially if you want to differentiate ASAP. i'm afraid i don't have a lot but i got pretty good mileage out of this:https://www.gceguide.xyz/files/e-books/a-level/Cambridge%20International%20AS%20and%20A%20Level%20Biology%20Coursebook.pdf
and talking of PCR reminds me of this protocol cheatsheet i need an excuse to scan, here's probably a good a place as any to dump it