I would get on to Apple - if it was sold with Leopard you should have Leopard discs. They supply machines with full discs (as you found) not just recovery discs like most PCs. They were fairly helpful with a friend in similar-ish circumstances. I suppose it was PCWorld who put Leopard on so you could try them - some hope!
What versions of iLife products do have? (iphoto, iDVD, iMovie). Your £30 discount may be outweighed by not getting it from Apple which I guess would have come with Leopard and iLife08. But you might not have wanted to hear that! I bought my iMac 3 weeks before they brought out the new model
