Ha ha OP!
Little babies are cheap.
My son got his first shoes at 14 mths. He then went through four sizes IN A YEAR that was £120 on shoes alone.
Mine (now 6 and nearly 4) go back to school/nursery in Sept. They both need new winter coats (£80), new school shoes (£80) new wellies (£20), new trainers (£40), new waterproof trousers (£18).
My DS needs new school shorts and new school jumper (£40). My DD the beanpole needs an entire new school uniform (2 school jumpers (£20), one skirt (£10), one pinafore (£12), two sets of polo shirts (£16).
Then they need winter boots for out of school (£80) plus warm winter jumpers, tights, new skirts and jeans and my son needs winter trousers since his old ones don't fit. God knows how much that will be, praying friends will hand things down tbh.
Then between them there is one birthday party a week on average (£40 a month on presents/card/wrapping paper.)
Then there are ACTIVITIES. Shudder. Piano lessons - £80 a month. Swimming lessons - £50 a month and nearly twice that when DS starts.
Extra nursery hours plus nursery hot lunches for my son - £120 a month.
Plus when you are feeding four rather than 2 it is MUCH more expensive at the supermarket.
Of course you can do it all for cheaper than the above, and indeed many people less well off than we are have to. But it is still v expensive!