He has to have your consent to take the kids out of the country, and in absence of your consent, an order from the court. I think someone already mentioned upthread a court is likely to grant this for a holiday.
But, if you have concerns about the child travelling for a long period of time, and you do not think it is in her best interests, and you think he might take her without your consent (e.g. saying they are going to Spain but going to (e.g.) Pakistan instead), then YOU can apply for a prohibited steps order that will prevent him leaving the country until or unless he provides you with flight details, accommodation details, return date etc.
The court are still likely to permit him to travel with her, but it will be on the proviso that he provides information, which you don't currently have. If he told the court he is going to Spain and then goes elsewhere, then that is child abduction as it exceeds the permission given. If he retains her, it exceeds the permission - and may become child abduction.
BUT, an order would depend on whether or not the destination country was a signatory to the Hague Convention. If it is, then the court are less likely to be overly concerned, if it isn't, then the court may be more cautious on granting permission.