Hi @ReeceOp,
Make sure you've completed the prologue in story mode. Secondly, go to your LSPDFR.ini (found in your 'lspdfr' folder in your GTA Directory) and set the PreLoadAllModels = false.
If that doesn't work, try going onto your RPH settings, and not loading any plugins on startup. Then open the RPH console (F4 by default), and type 'ReloadAllPlugins' if you spawn normally. You should then be able to go on duty by entering a station.
If you're still stuck and frozen:
1. Pause the game and put a waypoint on the map.
2. Unpause and open the RPH console (F4 by default)
3. Type 'Teleport' and select the waypoint version using the arrow keys on your keyboard, then tab to select it. Press enter to launch the command.
4. It should teleport you out of that area, to the waypoint, and force a fresh area load.
Let me know if any of those help.
Thanks,
Zen