The development of new generation, high-performance devices, such as MRI scanners or high-energy accelerators, (may be attributed to the use of) Nb3Sn based superconducting (SC) magnets, which are characterized by their ability to produce much higher magnetic fields than the presently used NbTi-based magnets. Due to the wind-and-react technology of the production of Nb3Sn magnets, new methods and materials for the magnet coil electrical insulation are required. The proper design of SC magnets demands the characterization of thermal properties of the new insulation materials, inter alia, in superfluid helium conditions. This paper provides experimental data of the thermal conductivity and Kapitza resistance for S-glass fiber reinforced ceramic-epoxy (LARP type) electrical insulation, measured in pressurized (at 1 bar pressure) superfluid helium in a temperature range of 1.50-2.00 K.