Redundancy notice period

Hi all...quick Q I hope you can assist with.
I am taking voluntary redundancy and have agreed the end date and have holidays still to take, am I entitled to take them?
So I get 20 days a year and am ending at the end of July...so I would be due 12 of the 20 days right? Now I have only taken 3 days off this year so far...can I apply for the last 9 days at the end of July so I can finish up early?
Can these be refused to me if the company say they will pay me for them instead or am I legally entitled to take them if I want to?
What if I have worked up extra days as Overtime...am I also entitled to take these?
I'm hoping someone can give me some pointers on my rights on this as the company are refusing all my holidays and I'd like to know if I have any grounds for objecting to this?
Thanks.

When you can take the holidays will depend on your contract, usually employers have to be reasonable, but if you're finishing up before the end of the holiday year and it doesn't suit them for you to take the holidays, then can usually refuse. You are of course entitled to be paid for any holidays that you are not permitted to take.

From a social welfare point of view, if you take the holidays before the contract is terminated you will not get paid any Jobseekers payment due for the days that you get holiday pay for. If the contract is terminated, then any backdated holiday pay does not affect your Jobseeekers entitlement.

Cheers for the response, Ildánach.
So can anyone tell me....I ave only taken a couple of days leave this year and I assume I am entitled to half a year's allowance (10 days)...have I no grounds for getting these days off before I finish up the job?
I mean, if I start a new job immediately then my annual leave for 2011 will be right down as I did not get my first 6 months entitlement?
I think the company are just being awkward....they need to reduce the numbers but have nobody to do my work when I am gone so at a micro level they will struggle for some time so they want me here as late in the day as possible. Way I see it is they should be making plans for when I depart and the fact they are sluggish with this is the reason they will not give me my time off.
Note that the redundancy has been approved since the start of May so this is not a surprise I am leaving.
It really breaks my heart it has come to this and I may need to go out sick the last week or so which is something I abhor but I feel I have no choice as I have alternative plans and they wont give me my entitled days off (which I was led to believe I would get before the decision was made that I was not getting them).

Any ideas?
If I do go sick, what possible issues may I run into?