When I try to lock the car, It unlocks itself and toots as if the doors open, but all the doors are definatly shut, I checked the central locking fuse and it seems fine, Unsure of what else could be the problem, but it's a massive issue as I cant leave it at work unlocked.

Also Decides to work SOMETIMES. like if I leave it for 20 mins ,then try lock it, it'll work

Any suggestions?

Sounds like you need to replace the right hand doorlock/actuator. It controls the other locks and it is the major item when these issues crop up.
You can buy them genuine Ford or Ebay for a LOT less.

Added some more info, I've also noticed, the Interior light turns ON when I turn the car off even without opening the door, after a few minutes it turns itself off, and I can then lock the car