Rich here, Land Rover tech,
The air suspension on this truck is a complicated system and you will not be able to fix it at home just for the fact of the equipment needed just to communicate with the systems computers. One thing you can try to get on the road is to cycle the key from off to on 10 times. Depending on the fault in the system this will make the fault historical and allow the system to operate again unless the fault is a hard fault and can not be cleared before repair. One thing you can check at the house is to see if the air compressor is coming on, we do have a high failure rate of those. It is located under the truck on the drivers side encased under a black plastic cover in front of the rear wheel on the outside of the frame. If you start the truck and listen in front of the rear wheel you should hear a compressor pumping noise, if not it is probably bad and the new one will likely need a new software programmed in when replaced.The dealer is the only one who is going to have that.But maybe this will help you to be able to drive it in.
A reman compressor is around 460.00 and a new one is around 730.00 in parts. please leave me feed back if you have the time.