You'll usually have to pay out quite a bit of money when you first move in. Most landlords will expect a month's rent as a security deposit and insist on rent being paid in advance. If you're on a low income, you may be entitled to housing benefit to help you meet the cost of your rent, but this is always paid in arrears. Make sure you get receipts for any money you pay out and keep these safe.
Landlords usually ask tenants to pay rent at the start of the month. This means that you may have to pay a month's rent in advance as well as a deposit before you move in to your accommodation. You may be able to get help to cover this rent in advance.