Actuarial adjustment and extra tax

I am about to be made redundant and am entitled to, amongst other things, a monthly payment of £1,212.12 until I reach the age of 60 which is exactly eight years from now. I have been told that the total value of this is £116,363.66 (which I agree is accurate) and it will be paid as an immediate lump sum actuarially adjusted.

1. What is the actuaruial adjustment and how can I calculate it to verify my employers calculations?

2. If I receive this lump sum then I will be liable to pay income tax on it at 40% whereas if I received the monthly payments I would only pay basic rate income tax. Can I claim that extra tax back from my employer and how can I calculate the amount that I should claim?

Thanks.

http://www.revenue.ie/en/tax/it/leaflets/it21.html might help with the tax part.

As for the actuarial adjustment, I assume it is some sort of present value adjustment because it is worth more to get a lumpsum now than to get it paid over 8 years. Interest rates are low are your lumpsum might be less favourable that if they were higher. But I'm bluffing here, you're best just asking your employer to see the calculation.