Other things to consider
How long do you want the tenancy for? A tenancy is usually a minimum of 6 months. If you are not sure, you can ask for a tenancy to be extended but remember there are costs involved in extending your fixed term tenancy agreement.
Start gathering together documents that your agent will need to confirm your identity, immigration status, credit history and possibly employment status.
You can also check out the government's How To Rent: The Checklist For Renting In England.