Legal advice: Can my ex really stop me seeing my son?

"Unfortunately, our relationship has broken down in the past few months and my ex has moved and taken my son with her..."

The Children and Family Relationships Act 2015 allows relatives to make an application for custody of a child.

Dear Stephen, 

I am farming at home on my parents' farm. I had a relationship with a woman with whom I had a child with, a little boy who is two years old, but unfortunately, our relationship has broken down in the past few months and she has moved and taken my son with her and she is refusing to give me access to him. What are my rights and what advice can you offer me?