Hi Geordee,
This is a bit late as I have just joined the forum but I thought I would add in our expenses to give you an idea of another family. Ours are on the high side as we live in South West London. There are 5 of us and we have a 9, 7 and 4 year old. We spent 130 on council tax, 150 supermarket (mainly Tescos but also Lidl and Waitrose), 100 gas and electricity with dual fuel discount, 50 car (we only use it a couple of times a week), 40 internet, TV, phone, 30 mobiles, 25 Thames water, 1,000 a year on insurance (building, contents and car) so 83 a month, my husband cycles to work so no commuting expenses besides his bike, 12 TV licence, 100 school dinners as they like to eat with their friends - we only do it in winter and they have a packed lunch in summer (2.20 per child per meal). So 720 total for us excluding mortgage and extras. But we're in London so council tax is more expensive than what you will pay. You may also be entitled to child benefit (around 20 a week for your first child and 13 for the next 3) although that has now gone a lot of people (if your husband earns more than 50,000).
This does not include other school expenses, uniforms, shoes and extras. As well as children's activities - swimming, football...
Make sure you sign up to Martin's Money tips to get good deals.
I hope it all works out!