How easy is it to replace both rear lights on an early L322? And is it a job I can do myself?

Also are the original lights for a 2003 version still available from LR?

Click image to enlarge

Click image to enlarge

Very easy to replace, if you upgrade you may need a resistor, ebay is your friend for replacement, not sure if LR are still doing them but if so they will be expensive relatively

Yes, as above, dead easy… 2 bolts you can see on the side with the lower tailgate open, and then you have to ease it straight backwards off some rubber sockets.

 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

I think you may be able to get an aftermarket lens and swap your cracked one, but never done it and it might involve glueing…..

 2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

If you try to remove the rear lights after removing each of the two screws they should pull to the rear of the car but probably won’t, they are likely to be stuck. I had this issue first time and resolved it by cutting a piece of softwood to a shallow taper and inserting the tapered end into the gap between the front end of the light fittings and the bodywork and gently tapping the piece of wood into the gap. This had the effect of driving the light fittings rearwards unsticking them.
You will then see the plastic clips that stick. Before refitting l greased the plastic clips and to date have had no further problems.