Reallly need help with movie name pleas answer?

Well it was a movie I saw a year ago where a brother and a sister are in Scotland, it is based in the future and it is where the world is undergoing a disease epidemic. It was either a disease epidemic or a zombie epidemic, but you do not see any zombies, just dead bodies on the road. Now I think it came out in 2004 or 2005. I want to say it was called, "One that gives the cookie". Can someone help? and no, it is not 28 weeks later.