"Why is only then touchscreen being sold if they cannot be separated from LCD..:O..? "
---> That's a good question! :P Digitizer is glued with the LCD panel, so you have to buy the whole set and use adhesive tape as Mr. ArHerning just said. Do not try to seperate.
Thanks so much! I'll probably get this: http://www.amazon.co.uk/Iphone-Touch-Pan...
@ Step 10: How a new LCD panel with the digitizer are glued again on to the metallic part???