Hello, I have just joined the site because I am trying to find some information.
The story
English Man living in Spain dies in road traffic accident, he leaves a widow living in Spain, and two children living in England, his widow living in Spain is his second wife and the step-mother of his children. He owned property in Spain, who will inherit the property? Does anyone have any advice please, regarding this matter.

As I think I understand it your children will have a legitimate claim on the property. Suggest you take professional legal advice, there might also be regional differences in the law.