In my design I have the ship tethered by a cable and a pipe that's delivering the fuel.
A better idea is the launch loop, but again you have to deal with cable weight and tensile strength.
In my design the vehicle would feed its rockets from an onboard fuel tank which would be constantly replenished from the pipe/tether. At detachment time it would still have a full tank to manage drag, getting up to final speed, and circularizing the orbit.