what a child needs when they come home is quite simply you, time, attention, love
Yes of course they need to be fed and clothed, toys etc, but they don't need expensive labels or even new stuff. Parks and many musuems are free, you take a picnic. It might be worth investing in a National Trust or English Heritage membership because then you have 'free' access for days out.
But start planning now, reduce your outgoings. Do you have the best utilities and mortgage deal? If not, switch. Get any house maintenance done now.
once I was approved I started stashing non perishable essentials and basics like pasta, rice, tinned tomatoes, cooking oil, cereal, fruit juices, cleaning stuff, toiletries, loo rol, cat food. I had about 6 months supply. Made a huge difference to my weekly shopping bill. You become a lot more away of bargains, vouchers, collecting nectar points - I save mine for Christmas and have a 'free' shop in December
I also invested in my 'mum' uniform. I kitted myself out with a good coat, shoes, basic clothes, I didnt buy anything for myself for a year.
Remember that you will spend a lot less on grown up entertainment and going out.
Take a long hard look at your current expenditure. Many people without kids fritter away lots of money on going out, take aways, coffees, randon purchases. Stop doing it now. A good thing to do is to try and live on one income now and see how you get on, where you need to save etc.