Get a copy made from your original key and fob.
Cobblers or Timpsons usually do them and can program certain keys and fobs too.
These cost around £40 from these high st shops - no proof of vehicle ownership needed or asked for!
Alternatively Landrover dealer will do it for around £150 - you must provide proof of ownership of vehicle, passport / driving licence etc.
From advice the programmed key & fob is ordered via landrover and arrives a week or so later.
I personally tried 'Cobblers / Timpsons' for a duplicate key for my 2001 TD4 and for some reason the key cannot be programmed correctly via these high st shops - although the machine copied the chip info from my key and gave the indication of a successful programming.
I was given 2 keys, both with fresh chips, both opend the doors but wouldn't start / disarm the immobiliser - so the TD4 wouldn't start up !!
After the shopkeeper apperantly did some research, he told me the key for the 2001 TD4 couldn't be done by them!
As someone previous has mentioned, take out a key replacement add on with your car insurance - some insurance companies give it for free!