We won't, not with anything resembling current technology. So, if we were to imagine a colonized solar system, there is a good chance it's not fusion that gets us there, but some currently unknown technology.
I'm not talking just about transportation, I'm also talking about the technology required to make an actually self-sustaining human colony anywhere outside the Earth. That is the part that only exists in principle - when you go to the details, we don't actually have any idea how we could build even a Mars colony that is truly self-sustaining, never mind one on a more inhospitable world.
Note that when I say self-sustaining, I don't just mean power, food, air, and water. I mean everything that a high-tech colony actually needs - plastics, machined parts, microprocessors, software, and so on.
You don't need a wonder technology to cart around the solar system, well, unless you are talking ECONOMICAL technology.
I'm not sure how expensive H-bombs are to make at scale.