So I have recently put in a reconditioned LT77 G suffix into my 110 Defender 200tdi. The mechanic put in a Britpart clutch. I am find 1st snd second a little crunchy and the gearbox supplier said this is down to the clutch. Does this make any sense?
Thanks

Thats because britpart = sh!itpart.

Did he put any oil in it?

Be inclined to think the clutch is maybe not disengaging properly.

Assuming oil was put in the box obviously

if it was the clutch you would expect it to do it in all gears, I'd be looking towards the gearbox.
I've had a britpart clutch fitted in my 110 for over 5 years without any problems

Maybe the clutch is dragging slightly. In my experience this makes the lower gear selection worse than the higher gears. Reluctant to engage, and a bit apt to crunch or make the car jerk as the gear is engaged, as if it is trying to move. It might be something simple like needing a drop more fluid in the clutch and a bit of a bleed. I'd try that first.

Many years ago we changed the clutch on a Vauxhall Viva and had this symptom very severely, especially with 1st and 2nd. We took it apart again and discovered that the bronze bush in the back of the flywheel had somehow got skewed over and rucked up as the gearbox input shaft had been forced into it. So it was binding. I've not heard of this happening on Land Rovers, but the symptoms suggest that something might be binding and not letting the gearbox shaft and crankshaft rotate independently when the pedal is pressed.