If you've left the police and want to rejoin you'll need to contact a senior member of the recruitment team or higher, names are shown below
https://docs.google.com/spreadsheets/d/1gf7x826gXxub6atwMp4HUrCqMTT9eWc4dOTwsAcmEsw/
You won't be able to see the application until you're a PC. You'll get a response (via PM) from a member of the recruitment team letting you know if you're successful or not and how to progress to the next stage.
The wait time is up to 24 hours