You can rent directly from a landlord or through an agency. When thinking about how much you can afford, you may find it helpful to work out your budget (see Managing money - Drawing up a budget).
Bear in mind that you will normally have to pay a deposit before you move in, which the landlord keeps in case of damage to the property and will return to you at the end of the tenancy – see Renting a home. There are rules about what the landlord can deduct from this deposit - for more information, see www.direct.gov.uk.