Generally, when you get promoted you should receive an updated section to your contract stating your new postion, salary, working hours etc and a clause at the bottom stating that your original T&Cs still apply, it's just the above that's changed. I have been promoted a few times and this is standard procedure.
In certain circumstances such as; if you're being promoted to an area that deals with Data Protection or similar you may be given an extra section to sign with the additional terms and conditions and that will be added to your contract in your Personel file.
Just make sure you get a copy of EVERYTHING they give you!
Hope that helps:)