No, your manager will not be able to view your payroll slip as this is private information. However, if a manager happens to have role within HR/Payroll admin, then then they would be able to access the payslip of employees.

Even with this access, managers will not view payslips unless they have a valid reason to do so or consent.

Payslips are online under the ‘Me’ tab. You can view and download your actual payslip, check the net pay and the bank account to which it’s being sent and view a graphical representation of your pay and deductions.

Payroll cut off dates and Pay dates can be found here - Payroll Timetable