This is a really useful thread - all sympathies to those who are going through this, as I did last year.
Just to emphasise, ladies, because I was very slightly surprised at those who haven't started yet (but maybe that's because I'm in London, where parents are in hysterics about admissions from the point of weaning): get your skates on! The deadline is even earlier than January in some areas - in my borough it's December - and if you missed it you're up the chuff.
Also, allow plenty of time for researching your options and the admissions criteria: they vary markedly, and you have to read the smallprint. Many local authorities publish information on who got in last year, and how far away they lived - some schools, particularly in urban areas, take in children from a shockingly small area. (I was told by the head of my nearest primary school that I lived too far away to have a good chance of getting in - I lived just 0.2 miles away. He was wrong - I did get in - but people in my road didn't.) But be aware of what can change from year to year. In my area there is a general shortage of places, and all the primaries take turns to have a bulge class each year - it rotates around between four schools. We were lucky enough to move into the area in the spring and get a place at an excellent local school - in fact, some people moved in just weeks before term started and got a place. But the next year the bulge class was elsewhere, and people living in my road who had applied on time were denied places.
Understand that the right of appeal is really limited. You have to show that the process has been applied wrongly, not that insufficient account has been taken of your family's convenience. The council doesn't care about your family's convenience, sadly. And they interpret exceptional social and medical need very tightly. Again, in my case, I was in the position of adopting a baby just before school started, and facing the possibility of having to take her on four bus journeys a day, just as she was trying to settle into her new home. I thought, as looked after children are so high in the admissions criteria, that was worth bringing to their attention. But the council was only interested in the school-going child being Looked After - they wouldn't even consider the needs of a Looked After sibling.
Finally, a cautionary tale with a happy ending. I had a lovely mummy friend in my previous area (inner London, very oversubscribed schools) who was intensely casual about the whole schools thing. There was a very good faith school near us. She didn't go to church but her dp reckoned they would get a place because he had been there as a child. I said to her a couple of times that the admission criteria doesn't include 'dad having been there' (maybe at Eton; certainly not at a state school!) but she chose to believe him and didn't apply for any other schools. Result: no school place. Even then, she was fully confident that they would win a place on appeal. I asked her what her grounds for appeal was, pointing out that she had been treated fairly according to the admissions criteria. She said, basically, "I'm going to tell them they should give us a place because dp went there". Result: no school place. BUT in the end they were allocated a place in a school that had been in special measures but is now on the way up. I wouldn't have even considered sending my child there, but actually it is a lovely school and he is doing well there. As others have said, even if you don't get the school you want, you may come to find that it all works out in the end.