You must only apply for a School Rep role in the School you will you be studying in during the academic year the role is for. Plus you may only apply for the level that you will be studying at. For example if you are a postgraduate research student in Newcastle Law School then you can only apply for the Newcastle Law School PGR position.
You can apply as a job share. However, both members of the job share must be in the same School and at the same level of study.
If your School’s School Rep position is currently filled or you are looking for a less senior representation role, then look out for Course Rep elections which take place in your School at the start of the academic year.