Hello, congrats on the interview.
I’d definitely brush up on your excel skills - YouTube have brilliant step by step videos. I’d expect a budget task - they’ll give you an anonymised 3 year budget for you to comment on expenditure and income. They’re likely to give you the staffing structure too. Staffing costs typically run at 70-80% of a school’s delegated budget.
Look at rates for pupil premium, sports premium, covid catch up, national funding formula, SEN funding, grants, formula capital, increased teacher costs for 2022 etc.
The other task could be a data one (teacher assessments input to mark sheets on SIMS and export to their assessment tracker software), HR scenario, H&S audit etc. One of my team recently went for an SBM interview, and one of the tasks was producing reports from FMS (the school’s finance system).
There will definitely be a safeguarding question, so ensure that you check who the DSLs are and know the reporting procedure.
Read the Ofsted report, research the school, go on the website, and tailor your answers to THAT school, not schools in general (HTs want to be flattered), don’t say you want the job because of the holidays/family life. Draw on your previous work experience, and stress how those skills will transfer to the school environment.
Good luck!