There is no law that you have to use an agent. However you will need to swot up on landlord and tenant law to ensure you know your responsibilities and find a rent deposit scheme for the tenant's deposit. You will also need the permission of your mortgage company, who may change your mortgage interest rate or require a specific monthly rental yield before allowing you to go ahead. Unless you know things about the future that we don't, there is currently no known way of protecting yourself against future uncertain events, although ensuring you don't spread yourself too thin is good advice as rates can only go up.