Answer:
A pay slip? I never heard of one.
You must be given your pay and a payslip within a "reasonable" time of the end of the period worked. There's no law to say in which order.
They have to provide, by law, a payslip but they do not have to (by law) provide it before you get paid!! If there are any discrepancies on your pay then any pay owed will be added (or deducted) on your next wage.
Are you being paid in cash? if so they may not be paying your tax
Not so far as I know.