We have the tech now for interstellar travel and we had it since the 1960s in the form of Project Orion - the only issue is that it needs a couple thousands thermonuclear warheads to work. And I'm sure better options will show up over time, as space infrastructure develops.
As for habitable planets - we already quite heavily modify the one we live one to suit us better (eq. I would freeze to death where I live without heating in the winter) so large habitats built from in space resources might be a better option anyway long term.
As for habitable planets - we already quite heavily modify the one we live one to suit us better (eq. I would freeze to death where I live without heating in the winter) so large habitats built from in space resources might be a better option anyway long term.