>>>Given constant accel, it would be a lot less time than that for a mere 100 LY.

If you assume that they can accelerate past the speed of light, and that there are no diminishing returns, maybe.

Keep in mind that the faster they go, the more fuel it will take to overcome the inertia of acceleration the interstellar hydrogen to the speed of the ship.

Also it should be obvious that they will spend much of the trip acceleration and decelerating. If they traveled at the speed of light the trip would take 100 years. Certainly given all the constraints, their trip would take considerably more than 100 years.