Perfect Fit Roller Blinds for a Bedroom?

If you are looking for light exclusion, which I understand is critical especially in a child's bedroom, I would not consider perfect fit roller blinds. 

Perfect Fit Pleated in a blackout cellular fabric is much better if you are set on using a perfect fit blind. There is still a little ingress but not as much as the roller version.

Otherwise, i'd possibly consider a normal roller blind fitted overlapping the recess. We'd usually suggest overlapping 50mm each side if you can.