Doesn't sound like the clutch. Sounds more like a clutch hydraulic problem.

Sounds like you are prssing the clutch pedal, and the hydraulics are bad, so, even though you are pressing the clutch pedal, the clutch not being actuated. That is why you are not able to get the clutch in gear. And, especially when it is cold, your synchromesh are going to balk and not want to let you in gear. When the tranmission oil warms up, things work a lot smoother, but you are actually putting a great deal of wear on your transmission, even though it may not feel like it.

Have the clutch hydraulics checked out.