Re: Holidays due from last year
nojob,
I was made redundant 2 years ago, and I received payment for holidays due and payment in lieu of notice as part of my tax-free settlement (ie tax-free up to revenue limits).
I'd suggest that decisions re taxation are not for your HR dept to make, but for Revenue. If you are taxed on this in your payroll, contact revenue for clarification and you will be refunded any tax you have overpaid. Revenue aren't there to con you, if you're due it back, you'll get it back.
One caveat though, the redundancy law changed since I went through my redundancy, although I believe these changes were to the benefit of employees so I wouldn't expect a problem there.
Good luck with it!