For 2004/5 Personal allowance is �4705 - this is the standard but if you have any perks of the jobs or if you have failed to pay tax in a previous job your tax free allowance may be different.
Therefore you pay no tax on the first �4705. You pay 10% tax on the next �1960, and then 22% on the rest (�2805).
Tax payabvle in the year then is �813.10 Obviously there is NI aswell