You would be subject to the Code on this project. The Building and Construction Industry (Consequential and Transitional Provisions) Rules 2016 provides that where both codes may otherwise apply, the Code takes priority.
This means that where an expression of interest was submitted prior to 2 December 2016 but a tender for the same work was submitted from 2 December 2016 onwards, the head contractor or subcontractor would be subject to the Code for the work. The head contractor would also need to demonstrate compliance with the Code requirements in order to be eligible to tender for and be awarded the work.
No. Your obligations on existing Building Code 2013 projects don’t change once you become a code covered entity. However, you’ll be required to comply with the Code on any new projects, including private projects that you express interest in or tender for after becoming a code covered entity.