My apologies for the delay.
You have two options.
You can make an application to the CMS - this will immediately override the Court Order
Since you currently have no income then you would pay a low flat rate until you find work
The downside of that is that if you do earn £40,000 and assuming the children do not spend more than one night a week with you, the ongoing monthly bill is more than £500.
The alternative is for you to apply to the court for a downward variation.
This is done using a Form A any paying the fee of £245.
The downside of that is being locked into what is a cumbersome system.
In addition your ex may discover that she will get more if she goes to the CMS.
At this stage you may wish to negotiate with your ex and point out that a court applictaion to vary downwards would be expensive and agree a short term reduction - but please please get it in writing.
Please ask if you need further details