It would not have sufficient separation SVFR, but it would be legal VFR. VFR for helicopter is clear of cloud, in sight of surface. So dropping through a hole to clear of cloud below is OK.
JohnR81,
SVFR is the less restrictive, not VFR.
SVFR in the London airspace requires a visibility of 1,000 metres. VFR requires 1500 metres.