Why would Mr Rimmer give Lewis Seddon a job in the school? His record of homophobia, violence and sexual harrassment might not rule it out - people do reform - but Seddon tried to murder Mr Rimmer.
In series 7, why didn't they given Tom the job as head of Pastoral Care? He's got a good relationship with nearly every single child in the school. Instead they give it to Ms. Chaudry, who the kids and most of the staff hate and has awful people skills?
The school in Rochdale closes down at end of series 7, and a replacement in Scotland opens at the start of series 8. It has boarding facilities so that a few students can finish their exams with the same teachers - but Scotland doesn't do GCSE and A-Level exams, they do Standard Grades instead. It seems the writers Did Not Do the Research.