Hahaha at the 'do teenagers really cost £300 a month' comment.
My dd today (perfectly typical day)...
Breakfast - porridge and punnet of blueberries - £3
Bus to school and back - £6
School lunch - £3
Food tech ingredients - £3
Phone - £1
Ballet after school - £10
Dinner - £5 (£3 piece of fish)
£31 already...
I haven't included 1 x third of our monthly bills (mortgage £500, council tax £250, elec/gas £125, sky etc £100, others £125) £1100 \ 3 = £400 ish so per day £10ish
I haven't included the cost of her school uniform (£500 this year, won't always be); or any of her other clothes.
I haven't included any contribution towards saving for holidays.
I haven't included anything like saving for big events, like birthdays, Christmas presents etc
I didn't include pocket money, or money for others birthday presents.
So, no £10 a day doesn't go anywhere near the cost of raising a child.