You could tell her that it isn't a holiday resort and she has to stop treating it as such

I suppose at this stage it's the only option you've got. I just don't get that if she wants to move out so badly, how can she possibly think she could run a household on any meagre wage she could earn as a checkout chick (not that there is anything wrong with that, you all kwim?) or any other low-wage job for unskilled workers (because that's what she is) unless she lives somewhere really dodgy or in shared accomodation and I think she'll soon realise that she aint the woman of the world she thinks she is when she's got overdue bills