Of the 350 nights when I was in Leek, I was able to observe on 110 nights (31%) although observing was only possible after midnight UT on 29 of these nights (corresponding stats for 2016 were 128 nights, 25 only post midnight).
For the period up to midnight, 16 nights were clear, with 51 having broken cloud or shorter clear spells.
The significance of observing stats does of course depend on what you are wanting to observe. Visual meteor watches require longish clear spells, whereas variable star observing can be quite productive even when there is broken cloud or when clear spells are brief.