just purchased a 2005 Cooper S. its missing an owners manual, any suggestions on the best place to purchase one in the uk ?

Here is a 2003 handbook in pdf form which should cover most things:
http://www.motoringfile.com/files/2003MINICooperCooperS.pdf

Have a look here:-

library of motoring > manuals (http://libraryofmotoring.info/reference/manuals/)

Thank you!