Robert Bussard first wrote up the Interstellar Ramjet in 1960 – 52 years ago now. Scooping up one’s fuel whilst en route makes possible high levels of time-compression thanks to relativity.
The typical flightpath would be roughly as follows…
Taking 10 years to Alpha Centauri and about 100 years to reach 40 light-years. “Fast” but not as fast as it might get, with continuous boosting. One problem with extreme relativistic travel is the dust and gas between the stars becomes a lethal energy shower. Protection becomes the big question above about 0.6-0.8 c.