The turbo on the Discovery 3&4 CAN be removed without removing the body, anyone telling you otherwise are simply not a skilled mechanic or are trying to rip you off by charging you for loads and loads more hours.
How do I know? I've done a few and cannot see why you would remove the body.
Now it's not a job for the faint hearted and you require a car lift, gas welding/cutting torch, some custom made spanners & sockets and you need to break the old turbo to remove it.
When the turbo is off you then modify the bottom bracket so it can use nuts and bolts instead of studs.
I can complete the job in around 12-13 hours or just over half the time if someone helps me (the charged hourly rate will obviously remain the same).
When you remove the body on a 10 year old vehicle especially a Landrover nothing goes back together perfect unless you replace a lot of parts and pipes etc so I would really not want to remove it unless it was vital. All of the body mounts will be corroded to the bolts, there will be tabs on electrical cables that WILL snap no matter how clever and careful the mechanic is and the will be brake pipes that will not undo.
So unless you are prepared to budget for new brake pipes, body mounts and other clips etc and more than double the labour I would not remove the body. Find a decent independent Landrover Specialist and have them do it as most are aware of the procedure to remove the turbo in place.