if you've lost you key you have to go into VW give them your V5 with VIN number and ID and they will give you a spanking new key fob from germany takes about 7 days to come costs £140 then £70 to get programmed to your car. i know it happened to me couple of months back i dropped my key in the canal lol.
forgot to include you have to get the car towed to the dealers to get the key coded in if you have AA/RAC/GreenFlag then your fine.