For helicopters:
OUTCAS:
VFR:
1500m horizontally from cloud or, clear of cloud, with the surface in sight and in a flight visibility of at least 1500m.
If not in compliance with the above, it must be IFR.
Can't do IFR from a private LZ. Has to be a licensed airfield. UNLESS you can guarantee clearance from obstructions below the MSA.
CAP793 refers to the layout and planning of an unlicensed strip/HLS.