You are missing the piece which says "A pilot may not."
In sight of the surface, clear of cloud & 3km is not technically IMC therefore may be flown VFR.
I think you may be missing the piece that says that, at some levels and speeds, in sight of the surface, clear of cloud & 3km
is technically IMC and may therefore
not be flown VFR, though it is within the licence privileges of a UK PPL.
The JAR-FCL PPL vs UK PPL issue is more complex. The JAR-FCL PPL has the following limitation:
(2) The licence is subject to the conditions and restrictions specified in paragraph 1.175
of Section 1 of JAR–FCL 1.
and 1.175 says:
JAR–FCL 1.175 Circumstances in which an IR(A) is required
(a) The holder of a pilot licence (A) shall not act in any capacity as a pilot of an aeroplane under Instrument Flight Rules (IFR), except as a pilot undergoing skill testing or dual training, unless the holder has an instrument rating (IR(A)) appropriate to the category of aircraft issued in accordance with JAR–FCL.
(b) In JAA Member States where national legislation requires flight in accordance with IFR under specified circumstances (e.g. at night), the holder of a pilot licence may fly under IFR, provided that pilot holds a qualification appropriate to the circumstances, airspace and flight conditions in which the flight is conducted. National qualifications permitting pilots to fly in accordance with IFR other than in VMC without being the holder of a valid IR(A) shall be restricted to use of the airspace of the State of licence issue only.
The effect of 1.175 on a JAR-FCL PPL issued by the UK can be argued both ways.