Planning a big family cost in the UK? Keep money for the goal in a separate...

https://high-wiki.win/index.php/What_Is_a_Sinking_Fund_and_How_Is_It_Different_from_an_Emergency_Fund%3F

Planning a big family cost in the UK? Keep money for the goal in a separate savings pot from your emergency buffer. Stress-test your budget with an awkward month of higher bills or reduced income, so you can spot a shortfall before committing.