First check that your local House of Fraiser stocks the 8GB iPod touch and if possible get them to put one aside for you. Call them on 01236 634567 or 0845 602 1073.
If they do, go to your local Tesco and buy £170 worth of House of Fraiser gift vouchers for £136. (Thanks to lucerysmum in this deal for the info: http://www.hotukdeals.com/deals/giftcards-20-off-tesco-includes-itunes-pizza-express-house-fraser-etc-12-1170193 ). As Tesco recommend - double check the terms and conditions on the back of the card before you buy, because they don't issue refunds.
Then go into House of Fraiser and pay for your iPod with the giftcard.