So at the moment you're paying your pension post tax anyway aren't you? So your gross salary and qualified earnings are the same figure?
So Im not sure if that helps you to know what they would do under salary sacrifice unless you have specifically asked?
Qualified Earnings for Employer Contributions are any earnings between £6,240 and £50,270 — so they essentially reduce the gross figure by £6,240 before calculating the 3% (up to £50,270). So for a £50k salary, QE becomes £43,760, and then 3% of that is £1,312.80.
I will double-check whether salary sacrifice affects the figure on which the QE is based, but I assume it will reduce it. So £50k less the Salary Sacrifice, less the £6,240 would = the £1,065.30 in the Scenario 2 table.