with the correct software it is possible to 'overwrite' the becm and get things going. If you can't find anyone i know a chap near me who can sort via post.
What happens if you charge the battery and then put the key in the ignition , early cars you need to press the lock/unlock buttons, later just putting the key in. If the locking out has not gone into complete lock down you might be lucky. otherwise its a trip to stealer;indi to sort.
Also have a look on Range Rover . net and find post from rick the pick. knows his stuff and will be able to answer any becm question.