A one month’s notice period has been served to one of our employees who has been working with us since last one year. We are confused as to what date should be shown on his P45?

The company gave notice on 25 Sep 2010. The company runs monthly payroll for all its employees till end of the month each month. In this instance which should be the date on the P45? Do we run his payroll till 24.10.10 or can it be run till 31.10.10? Do we need to take into account of SSP waiting days and any unutilized leave balances that the employee is entitled to take?

Any advice would hugely appreciated.