The engines included use the following as fuel-

Bussard uses LH2 as fuel
Daedalus uses FusionPellets
Epstein uses LF/O

For the Bussard and Daedalus engines, you'll need modded resources.
For the resources I suggest the mod Interstellar fuel switch:

https://forum.kerbalspaceprogram.com/index.php?/topic/106243-181-111-interstellar-fuel-switch-ifs-318/