I'd also recommend the Smallholding Manual from Haynes which I found really helpful as a great overview of where to start (and the author is active on this site too). Like Mad Goatwoman says, you need to think first and foremost about funding. We're in the South East because my husband works in London. It does cost a lot of money to buy a place with land here and you mustn't underestimate set-up costs - fencing, housing etc. Best thing to do is work out what you're going to do for your main form of income, find that job and then find a suitable house/land in that vicinity.
I've been keeping a quite careful record of my poultry since we got them last autumn and even if you just look at the variable costs - food, bedding, routine health care, it's cost us £1.50 per egg (and you pay that for half a dozen organic freerange eggs in the supermarket). Taking into account total costs such as housing and run, we're still running at over £10 an egg although that will reduce in time because we're now set up for bigger numbers than we have at the moment. In my case, I hope to get some money back from breeding or selling fertile eggs in the future - there's more money in that direction although I'm sure it'll still be pushed to cover costs.
I would also say that with two young children, don't underestimate the time required to manage everything. My husband works long, long hours so he's only really around at weekends (and not always then) and we have eight acres of land. So the vast majority of the work is done by me and I'm losing to weeds in many places at the moment. I have three children aged 7, 5, and 3 and the youngest is at home most of the time. She is old enough that I can leave her in the house while I go outside but she's not that keen on being out in all weathers. So while our halcyon dreams were of our children growing up building dens and climbing trees, that's not necessarily what they want to do (although it does happen sometimes). Every chore doesn't take up too much time but at the moment I have 12 ducklings in the kitchen which need cleaning out once or sometimes twice a day, a hen with three chicks in a run on her own, two more broodies sitting on eggs in their own runs, a further two hens (one of whom has been to the vets this week and required twice daily meds) and a cockerel in the main run along with an older duckling, four adult ducks and two geese. So just to feed each pen and clean out their water etc. takes a while not including the cleaning out of their houses.
Then on the fruit and veg side, this is the time of year for seeding, planting out and watering every day which also takes ages - especially when the hose doesn't reach. I've also got formal gardens where I'm trying to build up the flower beds with herbaceous borders so I've been growing lots of flowers from seed which all need potting on and watering. And most of our acreage is mown grassland which we mow every week and probably takes about 10 hours to mow the lot (with a compact tractor).
We've not even got any big livestock although we're thinking of a couple of weaners next year to turn into sausages later but I'm still busy full time and my children are not happy that I don't play games with them and have been heard to wish we weren't 'farmers' any more! Clearly now is a busy time of year but even in the winter I was planting fruit trees and doing various maintenance.
It really helps if you're handy - for lots of things I have to call somebody in (so far fencing, tree surgeons, hedgecutting and the odd DIY job). I did go on a fruit tree pruning course because I reckoned that was a good investment and we're getting bees so I've been on a course for those too. The sheep course put me off sheep so that's saved us some money on fencing (and now we're getting vines instead).
This is not meant to put you off because it's still very satisfying and I do always leap in with two feet so I probably always take on more than I should (I keep saying next year will be calmer because we've got lots of basics in place now but realistically we're starting building work on a holiday cottage plus some other improvements to our house, thinking about pigs, wanting a bigger poultry run, needing to convert a disused Nissen hut to a growing tunnel/internal poultry space - so the ducklings don't need to be in the kitchen next year etc.etc.). But you do have to be realistic about how much you can afford to do and how much you have time to do.
Good luck with the plans!
Hester