Club Kitchen is normally at Door 2L; i.e. at the bottom of the stairs.
Personally, on the few occasion I have been peckish during the flight, I have been able to find something I want. Never really seen a really depleted Club Kitchen. Crew normally leave a basket of chocolates, crips (chips in US-speak), biscuits on the wide shelve in behind 64C along with drinks. However, the plastic containers of pasta is in the Club Kitchen fridge downstairs.
The only time I use it is on the really long flights like LHR-SIN/LAX since I usually eat the first meal served on board.