Yes. If the taxable element of the redundancy package is your only taxable income in 2009, you will by the end of the year be able to claim your whole tax credits and standard rate cut-off points against it.
You can start claiming tax relief after 4 months' unemployment so you will get the benefit of one month's tax credits and SRCOP.
The Top Slicing Relief question is an interesting one. You cannot claim Top Slicing Relief until the end of 2009. The tax rate on the redundancy will presumably be 20% by the end of the year. It is likely that your average tax rate over 2006,2007 and 2008 was higher than 20%, so you will not get any Top Slicing Relief.
Brendan