In most cases, you cannot rent out a property that is financed with a standard residential mortgage without first obtaining permission from your lender. To do so without switching to a buy-to-let mortgage, you would need to request consent to let.
Consent to let is an arrangement where your existing mortgage lender agrees to allow you to rent out your home while your current residential mortgage remains in place. Approval is not guaranteed and will depend on your individual circumstances and your lender’s criteria.
Where granted, consent to let is usually temporary, often for a period of 6–12 months. It may also be subject to conditions, such as a requirement that you plan to move back into the property or sell it at the end of the agreed period.