You can apply for a Crisis Loan Rent in Advance but only once you have your deposit arranged and only if you have no other way of getting the money. You need to do it by post and you'll need to do it on Monday by picking up a form from the Jobcentre if you want it paid in time! You don't need to be on benefits but you mustn't have any other fundng like an overdraft.
You can apply to the Council to see if they have a Deposit Bond Scheme and then if they do whether the Landlord will accept that (they basically guarantee the deposit will be paid to the landlord if you leave the property a tip or defaul on your rent),
Don't call Crisis Loans Living Expenses, they don't do rent in advance except if you're homeless, have
no family and are moving in today! It'd be a wast of everyone's time.
If you can't get a deposit you'll need to find another flat, perhaps one where the landlord will accept just 1 months rent in advance OR deposit (h'll ned to state over the phone it's rent in advance NOT a deposit he wants and possibly explain why he doesn't need a deposit from you, i.e. he's taking it from you a bit each month on top of your rent). Also make sure you can afford the property, if you lose your job within 3 months what will you do? Make sure you can afford the rent on Housing Benefit (if your'e under 25 you won't be able to incidentally!) or you may end up in a legal battle with the landlord as you're liable for the full tenancy charges.