Key Replacement

As the title indicates, I just lost my key (both now lost) and have messaged about getting a replacement. I am living in Central London, so does anyone have experience with getting a replacement key for the battery (Cruiser) and how long it usually takes? Are there any workarounds to the waiting time, and do they need any specifications from me to make sure they are shipping the right key that will fit my battery? Thanks for any pointers!