Either you've been given wrong advice or you've misunderstood the advice you've been given.
Scotland is a different legal jurisdiction to England and Wales, but when it comes to moving your child from one to the other there are no restrictions, contrary to what there would be if you wanted to remove a child to outside the UK.
It's s13 of the Children Act that prevents external relocation without consent:
(1) Where a [child arrangements order to which subsection (4) applies] is in force with respect to a child, no person may—
(a) cause the child to be known by a new surname; or
(b) remove him from the United Kingdom;
without either the written consent of every person who has parental responsibility for the child or the leave of the court.
Common Law has further made very clear that removing a child from the UK requires the consent of all those with PR, whether or not there is a court order in place.
The leading decision in this area is Re C (Internal Relocation) [2015] EWCA Civ 1305. In this case the judge said that there is no need to show exceptional circumstances, and that the court should approach such cases in the same way as it would applications to remove from the UK.
The main difference is that the parent seeking to move the child to another UK country can simply up sticks and go without the consent of the other provided there is no existing court order preventing that, and provided it does not breach an existing order for contact or shared residence, or change the child's school.
The courts would prefer the parent who leaves to apply to court first for permission to go, but that is not strictly necessary and the usual application is made by the parent left behind.
There is no presumption that, having already been taken elsewhere without the consent of the father, the child should be returned to its home country. Re R [2016] EWCA Civ 1016