Hi Caspar
Based on the numbers you have provided, your current monthly income is €6,100 and outgoings are €4,877. That leaves a surplus of over €1,200 per month for stuff you haven't accounted for in your outline above.
If you got job sharing, your monthly income will be approx. €4,600 and outgoings €4,677 (€4,877 - €200 reduction in childcare costs). While it is manageable, you'll be losing a surplus you have invariably gotten used to having!
Try doing up a monthly budget and account for every penny that gets spent. That'll help you identify where you could cut back, and perhaps figure out where that extra €1,200 is currently going!!