2000 Corsa TD 45k very very hard to get into or change gear

Hi, I have a year 2000 corsa diesel, about 45k miles on the clock. clutch hasn't been changed. when i bought it last year i noticed that changing gear was not as smooth as i would have liked, but it was tolerable. over the past four months, it has gotten intermittently worse. it doesn't matter if the car is warm or cold, or how long the journey is. getting it into first gear is hardest, and puts up the most resistance - i have started taking off in second gear and not trying first at all. it takes two hands to get it into first and i just go into second moving off from traffic lights. fourth to fifth isn't as hard, and second to fourth isn't as hard. i dread putting it into reverse when starting as it can take three or four very loud crunching goes to get it in, with the clutch to the floor. it feels like i am forcing it into gear, and it seems to bump during gear change - from third to fourth it bumps out of third into the middle and them bumps down to fourth - there is nothing smooth about it. i know nothing about cars, but am posting here as i brought the car to a garage for an mot service and they saw nothing wrong with the gearbox or clutch (i told them it was getting harder to get into and to change gears and asked them to look at it, as i wanted the problem fixed whether it was needed for the mot or not). this was four months ago, and i told them that it was starting to get hard for me to get it into gear. many thanks for your advice!