They're 2 really different subjects. I think it's probably most realistic to specialize in one of them, rather than both. Biogerontology is where you grab some short-lived critters, watch them age and die over time, and try to intervene, and then nobody knows what the result might mean for humans. Regenerative medicine is where you try to grow replacement parts, inside or outside the body, and nobody knows how to get that to work in a way that's useful for patients.
So, you might pick up from my tone, that I would view humanity's overall level of capability in either of these fields as being rather low. I mean, obviously it is. If it wasn't then we would have figured out what to do about your and my aging, by definition. And that has consequences for how to go about studying them. Since nobody knows how to make biogerontology relevant to humans, or to get regenerative medicine to work at all, then means that whatever you can learn from reading books or taking classes is at least equally limited. People who advocate applications in these fields are necessarily peddling hypotheses, rather than facts, because there aren't very many facts known. This runs some risk of actively misleading you (e.g. see the debates in Sci Am from the turn of last century, about whether powered flight requires feathers or flapping, while 2 kids in a basement with no access to external capital where unboxing massive metal objects).
So I think you're already on the right track with studying biological principles, (and not any particular hypothetical applications). If you can deepen and broaden that, you'll be in the best position to figure out applications that can be had.
And yes, I think it's absolutely critical to get access to test "subjects" (biogerontology) or a lab (regenerative medicine). Theoretical study in a vacuum takes you only so far. In an early-stage field like these, breakthoughs don't come from theoretical reasoning, because there isn't enough stuff known to reason with. Breakthroughs come from doing stuff, and paying careful attention to what happens. There are some ideas about how to do science without massive financial backing scattered around Longecity and the Internet at large. It can be done, although the people who do this well are still precious few. "Diy biology" "biohacker spaces" and things like that are good search terms.
