Peugeot 307sw with oil in the water bottle help?

Our peugeot 307sw has just developed an oil leak into the water system some how, there is no evidence of bubbling at all but has to be a head gasket problem. it is an 02 plate and only has 47k on the clock with fairly regular servicing by peugeot. if there are any other possible causes could someone post. We bought this sheap off of my folks and its been more like a poo go than a reliable car and my mrs isnt happy. thanks in a dvance for any help

Malcolm Martyn
January 2010