There is a folding wooden ladder available at most stores.
This is attached to a loft trapdoor, the whole thing folds up into the loft.
It fits a floor to floor height of just over nine feet and you cut it to size.
The best value for money that you will find is the 3 section aluminium loft ladder by Lyte Ladders called the Easiloft. It has a maximum load capacity of 150 kg and comes with a handrail, operating pole and a kit to convert the loft hatch to the swing down type. The ladder is very sturdy yet light and best of all it is very simple to fit. You can buy them on Ebay for only £41 or from Pryde & Sons Ltd in Glasgow.