On actual numbers, I'm now out of the loop as my youngest is 6 - but to help you budget:
Price up 2 packs of nappies and a pack of 4 wipes a week.
If you formula feed, a tin a week is about right. (Less at the start, more towards 6 months, drops off when you start adding solid food).
Your house will go from being empty in the day to used, so gas and electricity bills will increase. You might use your car more.
Clothing wise, they grow fast in the first year! But the speed they grow, the supermarket clothing is fine, have a look at baby grow prices when you are in there. Assume need to kit them out every quarter for the 1st year, then 6 monthly. You can reduce that cost by buying second hand. You will be given a lot of clothes as well.
If you will be at home for a long time, budget money for going to baby classes like baby massage /sensory classes/ makaton classes /toddler groups, not just for the baby, but for you to get out and meet other mums. It can be very long lonely days at home if you dont.
The big cost is childcare, I took a year off after dc1, then it was £50 a day in childcare (outside M25, commuter town for London), believe my dcs old nursery now charges £65 a day, worth calling local ones to you as it varies greatly around the country. (Also many will do earlier drop offs than advertised, but you will have to pay a little more).
With nurseries, worth checking out their preschool if they have one, makes life a lot easier if you can keep them there for preschool and knock the 15 hours off your bill, rather than try to move them to another preschool and use a childminder to do the run.
We didn't do shared mat leave (dh was the higher earner), friends who did had mixed reviews of it - from an outside point of view, how successful it was depends on if the mother can let go about her way of doing things and let the father find their own routine, and if the father was hands on before swapping the leave.