How can i get the code for my Ford Fiesta 3000 Traffic cassette radio?

Just had the battery go on my fiesta and have now found out that none of the previous owners wrote down the radio code in the book, plus im still a bit poor from buying a new battery.
So i was wondering if anyone could help me find the code to unlock my radio, rather than go to Ford who want £15 pounds to get a new code?

Serial Number: M018935
Part Number: XF6F-18K876-GA

Thanks for any help you can offer.