Rotorspeed, from what I've read so far, 800 metres visibility is likely to be required for Part NCC operations.
I haven't seen a minimum cloud base laid down under those new regulations. But it makes sense for it to be high enough for a Class 1 departure profile to be flown as far as the increase in IAS to Vy to be achieved in VMC.
There may be some regularly used private sites in UK where a Vmini climb needs to be held for a protracted period but I haven't experienced them. I would always aim to climb at Vy iaw the profile being flown. For PT operations this would be mandatory anyway. Although flying in a private capacity, I always aim to fly to Class 1.