Basically acrimonious divorce I have alerted various establishments
In the past for updates pertaining to children's education eg school reports
Medical Updates From Doctors etc. However court order stipulated I can
(Equally) travel abroad surely If the courts have granted permission this
Entitles access to children's details if resident parent is obstructive.
I believe Passports belong to HMPO and neither parent can demand they
Should be the ones to retain them. I am sure you concur divorced couples
Are entitled to details of their children's Passports and the aboved
If your child arrangements order provides you both with leave to take the children out of the UK for holiday purposes (usually due to a joint "lives with" order - or specifically stated in the order), then your ex shouldn't be refusing to provide you with the passports - unless you are a flight risk. Does the order state which parent is to retain the passports, and the circumstances under which they must be released to the other parent?
Where parents are in conflict over who retains the passports, or where one is refusing to release them to the other parent with just cause, then it is possible to arrange for a neutral solicitor to hold them, with the instructions to not release them to either parent with written consent or the appropriate court order.
If you have a holiday booked and paid for, and she is refusing to hand the passports over, then I suggest you write a short letter strongly requesting the passports so the children are able to enjoy a holiday and that should she refuse (without just cause), you will seek resolution via court, including compensation for your missed holiday.