I've just developed a similar problem with my valver.
Pulling away and heard a clicking noise when engaging the clutch, and felt a small vibration through the pedal, and now I struggle to engage first and reverse when the car is stationary.
I'm thinking it could be the self adjusting mechanism has given up and the cable has slipped slightly resulting in the clutch not dissengaging at full pedal stroke and consequently gear selection is difficult. I've experienced something similar in an Elise in the hot weather where we couldn't get the clutch to dissengage fully as the hydraulic pipe was expanding.
Haven't confirmed it yet but could be worth a look,
Good luck