RTI & holidays

Not looked into RTI in great detail as yet but a thought occurs to us.

If a small accountancy practice runs payroll for some of its employer clients what happens if they go on holiday for 2 weeks in the summer and close the office? They are not physically present to run the payrolls under RTI at the "real time".

Run them early?

If so what happens if the accountant returns to find one of his clients' employees didn't come in that week, was off sick, has been sacked, has died.