I've been through redundancy a couple of times. Check very carefully the terms of what is being offered, and also the details of any credit agreements you have in place (mortgage, loans, cards). In the majority of cases, although the redundancy terms may seem attractive, if you opt for it voluntarily any payment protection insurance you may have WILL NOT PAY OUT. They will treat you as if you just left your job of your own volition.
For redundancy in general, companies are required to go through a specified consultation process. If less than 100 employees are for the chop this period is 1 month, any more and it's 3 months. Whichever, get the terms and parameters of the consultation agreed as quickly as you can - once these are signed off, the remainder of the consultation period is paid to you tax-free.