In Class G, almost nothing is mandatory.
IO please check out rules 20, 33 and 34.
If you are not VMC, then you
must comply with the IFR (rules 33 & 34 outside controlled airspace).
Rule 34 (quadrantal rule) :-
Quadrantal rule and semi-circular rule
34 (1) Subject to paragraphs (2) and (3), an aircraft in level flight above 3,000 feet above
mean sea level or above the appropriate transition altitude, whichever is the higher,
shall be flown at a level appropriate to its magnetic track, in accordance with Table 1
or Table 2, as appropriate.
(2) For the purposes of paragraph (1), the level of flight shall be measured by an altimeter
set:
(a) in the case of a flight over the United Kingdom, to a pressure setting of 1013.2
hectopascals; or
(b) in the case of any other flight, according to the system published by the
competent authority in relation to the area over which the aircraft is flying.
(3) An aircraft may be flown at a level other than the level required by paragraph (1) if it flies:
(a) in conformity with instructions given by an air traffic control unit;
(b) in accordance with notified en-route holding patterns; or
(c) in accordance with holding procedures notified in relation to an aerodrome.
(4) For the purposes of this rule 'transition altitude' means the altitude which is notified
in relation to flights over notified areas.
11 January
(my emphasis).