Take the key fob and slide the metal top off it. There's an arrow to show which way. Inside is a proper key. Look at how it's positioned before sliding it out as it's not obvious when you come to put it back. That's it. A key. Remember when replacing it to slide the top the opposite way to the arrow.
The other option is valet mode from the front screen- at least it is on the f type and I'm sure I've seen it somewhere on the fp.
Depends when you want to lock it and for what purpose as valet mode also locks boot and disables the stereo and limits speed etc