Sorry I didn't see your post Emily we must have posted at the same time.
There's no guidelines really. It's down to your own persistence. They list the available houses and you have to register your interest in it (they call it bidding) then the person with the most need (graded as a b c and d, we are c for minor over crowding) gets the property.
Dh won't bid on anything because he doesn't like the areas or they are too far. And while the areas used to be bad, not all of them are any more, and I do agree on not wanting to go too far but I'm reality they are not too far, most of them are within 5 miles.
I found a private rent the other day, it is massive! The front room is bigger than our whole down stairs here. And only £200 more a month, which anything in the village is £4-500 more a month. But as it boarders an area he doesn't like he said no.