When going through the gears both up and down, the gear selector is very hard to get in and out of gears. I have to push the clutch hard up against the firewall to get it in and out but is still a struggle.
Can anyone please suggest what might be going on here...

I have a ED XR6, 5sp manual

Try to adjust the clutch pick up point. U can do this by turning the nut where the clutch cable goes through the firewall [in the engine bay] clockwise. If this fails check the oil level and top up. There is a plug on the side of the transmission to check the level.