Agree with BT's suggestion. The Timpsons stores that I know have a machine to check the original key, and then can advice if they can cut another key to suit. Be warned though, that not all key codes are available to Timpsons.
In which case, look around locally for places advertising vehicle key replacement cutting, and ask there. Where I live, there are four outlets that seem to have all the equipment, but it doesn't come cheap. And total replacements of a vehicle locking system isn't either, especially from main dealers?.
Ill say timpsons as well
I needed a spare for my Citroen c3,plain key doesnt do remote central locking just put key in door,£60 good for a spare,if i wanted it programmed cost was £100 or £232 from citroen!
There are several mobile locksmiths in our area, I found the one that I used via a simple Google search. He came out with the blanks, copied the mechanical key from the old one, plugged his laptop into the service port of the car, went on line and found the code needed, flashed the EEPROM inside the new key and checked that it started the car. Start to finish 20 minutes and £90, this was for a 2009 Ford Focus.
In my earlier post I suggested similar about outlets being available. Agree with what you say, but have found that going to the 'locksmiths' own premises, can reduce the price to about £60.00 (no call-out fee).