Hi there,
My 'payroll' experience is limited and i'm sure other's will know more about this, however, I found this
http://www.qck.com/paye-guide.html which should help you start to research exactly what you need to do.
(a brief read of it seems to suggest you'll be responsible for working out your tax either by submitting stuff to the Inland Revenue or using a Tax Accountant. A 3rd option is to buy Tax Calculation software and feed the figures into it, let it calculate for you and then file online!
I used to work for Intuit, and was part of the Tax Product in terms of software development, so I have a gist of the Tax laws but nothing concrete enough to advise you directly.
If you search more, there's quite alot of sites which discuss tax, PAYE etc etc and I'm sure you'll find more info!
Cheers! DtM - West London & Slough UK!