For civil aircraft, but the RAF operate VFR at night and I have certainty received numerous VFR clearances at night from military controllers when teaching night flying in a civil aircraft from a military aerodrome.
Whoppity what you say is true for the military, but as you appear to be a civilian pilot, flying a civilian aircraft, the ANO and rules of the air apply to you wherever you are flying from, military or civvy.
Rule 20 clearly states:-
Choice of VFR or IFR
20.—(1) Subject to paragraph (2) an aircraft shall always be flown in accordance with the Visual Flight Rules or the Instrument Flight Rules.
(2) In the United Kingdom an aircraft flying at night shall—
(a) be flown in accordance with the Instrument Flight Rules outside a control zone;
(b) be flown in accordance with the Instrument Flight Rules in a control zone unless it is
flying on a special VFR flight.