Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
How is the child's time shared between you?
What is the problem with him missing one day at playgroup?
I am afraid that it in fact amounts to Child Abduction
In addition your ex will be able to apply for an Order in the UK forcing you to return to NI with the child.
If you wish to move to the Uk then you will need to apply to the Court in NI for permission to remove the child
Alternatively you can apply to the court for a Specific Issue Order ensuring that he takes the child to Playgroup
Sorry not to hive you better news - please ask if you need further details
You are most welcome - I hope matters go as well as they can