Income tax and contributions to a pension scheme?

For a variety of reasons I am likely to have underpaid tax in some of the last few years (unearned untaxed rental income). I am in the process of straightening things out, but seem to remember from years ago that contributions to a pension scheme are allowable for tax and that if someone buys a pension they can spread the cost back over a few years to receive tax relief as if the pension had actually been purchased in that year. So, if a pension is bought for say £10000 the cost could be set off against taxable income in the say the previous 4 years at £2500 in each year.

This is probably quite complex, and so if no-one knows a straightfoward answer perhaps they can point me to a suitable book or website for the info. Thank you.

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Annuities