I had this problem a couple of years ago - I had got into Lancaster as my insurance but didn't receive an accommodation offer. Lancaster's policy is to let clearing students have priority over on-campus accommodation so I'm afraid it's very unlikely that you'll receive an offer.
I didn't hear anything from the university about accommodation until the beginning of September, where they said that my application was unsuccessful - however they said that they still had limited places available in halls-style accommodation off-campus (Cable Street and CityBlock), and that there were spare places at the University of Cumbria campus available as well. Not having any other options and only a couple of days before everything was taken I chose CityBlock, and received (and accepted) an offer for a room there about a week before the move in date.
To be honest CityBlock is a dreadful place to stay, especially in your first year (and I've heard bad things about Cable Street and Cumbria as well), but if you've got no other choice it's best to apply for a room there as quick as you can to avoid ending up with nowhere.
Regarding colleges, as far as I know everyone living off-campus in first year (or at least everyone in CityBlock) is automatically assigned to County.