Can purchase replacement glass separately from LR
The glass is available from Land Rover separate from the assembly. Take your serial number with you as there are different flavors of the glass - concave, heated, tinted etc depending on lots of stuff.
The new glass clips in with some difficulty. Hence practice on the broken piece if you can. Remove it and reinstall it a couple of times as most owners break the new replacement glass because they push on the perimeter of the mirror rather than the centre.
Look at the plastic 'clips' on the back of the mirror glass, and you'll see the top has to first latch onto the round motor assembly in the mirror housing. With that clipped first, then the bottom clip should click into place as you push the glass back into the housing.
Make sure the glass is level when you push it in, and it might take a few attempts but you will succeed.
Hence if you can practice with the cracked piece, your first try with the replacement glass just might be successful.
