I googled "Peugeot 307 Owners Club" and turned these two up.
http://www.clubpeugeotuk.org/http://www.peugeotcentral.co.uk/index.phpEven before the internet, I found owners' clubs the most useful. Someone always knows someone with the part you want and they won't charge an arm and a leg.
I remember dealing with two of the better scrappies in Somerset and they had some form of computer network that could locate parts from another breakers if they didn't have it themselves.