Unlocking phone and leaving contract

Hi,

i have tried to get questions answered on phone on phone and keep getting cut off even after waiting for ages on hold or being passed around.

If if I want to leave my ID contract is my phone locked? How do I get it unlocked? Does it cost? Which department needs to do it?

If my contract ends on 8th Jan, what date do I need to give notice on to leave without incurring any costs?

thanks