Is there a way to have the car auto-lock or alarm so if you forget to lock it, it'll sort itself out or at least let the bells go if a door is opened?

Autolock after unlock I believe is a programmable option.

This means if you lock the car, put the keys in your pocket and it unlocks by accident it will re-lock after a few minutes as long as a door isnt opened.

Under no circumstances will it lock the car if you just leave it unlocked. What if you left the keys in the car etc? No cars do this, it's part of the thatcham category I believe.