You have a path from earth to a planet 40 lightyears away. There is a planet every K meters that can house a fuel tank to serve as a checkpoint. Let F be the amount of fuel to take a ship between two adjacent planets. Let 0 be the first and L be the last checkpoint.

Suppose a rocket can hold 3F. Go to A, deposit F, and return 2 times. Next rocket goes to B, stopping at A each way to take F -- do the B trip two times. Now you have two tanks at B and none at A. Repeat like binary addition till you fill L-2 with F, then repeat for L=L-3 to L=0. Now each checkpoint except the last and next-to-last has 1F. A final ship can make the trip to the planet, build a civilization, find a fuel source and return with pics.

Are we willing to use a railgun, with a rocket burn at apogee? (So one-half orbit from the starting point: without the burn, the object will hit the ground when it completes its orbit). If so, a lot less than is needed by pure rocket burns, where you have to carry all of the mass used to accelerate to orbital velocity.

Step one, find an asteroid with ice...

The best way would be to use a space elevator pipe for this. But it's still not feasible.

Better off Enceladus. A ship that size probably would be built in space.

If you make the fuel on Mars it will take less effort to get it into orbit. It's also a bit further up the suns gravity well.