Your understanding is mostly correct. Base on https://en.wikipedia.org/wiki/Hawker_Hurricane_variants, The Hurricane IICs had two fixed 44 gallon tanks in the wing centre-section, which were the main fuel tanks for the aircraft. The Hurricane IVs had the same fixed tanks, but also had the option of carrying drop tanks under the wings for extended range. The drop tanks could be either 45 gallon or 90 gallon, depending on the mission.

Base on https://en.wikipedia.org/wiki/Hawker_Hurricane getting over it, The Hurricane IIc night fighters did not have drop tanks, as you said, but they did have an additional internal tank in the fuselage, which held 33 gallons. This increased the total fuel capacity to 121 gallons, which was enough for about four hours of flight time.