he is 4 and he lives with me sunday to friday and stays at his dads friday night to saturday night. but sometimes just saturday day his dad is not the most reliable person

Hi My husband is step dad to my eldest boy and his biological dad has parental responsibility. We meaning my eldest son and my 6month old son and husband all live in Southport UK and my eldest sons dad lives in Bootle Liverpool but we as a family are looking at moving to Cumbernauld Scotland. Can my sons dad stop us if he has parental responsibility. Especially if we are saying we will bring him to him during school holidays and pick him up during school holidays this meaning he has no travel cost at all and would see him for 52 days during any of the scottish school holidays which is the equivalant of what he has him now he has him every saturday now. PLEASE PLEASE HELP!!!!!!!!!!