Read the break notice to make sure it meets your needs. Check that the landlord and tenant details, and also the property address in the notice are correct. Ensure that the original tenancy agreement includes a break clause that allows for ending the lease early before proceeding with this break notice. Also bare in mind that there may be a specific notice period you must stay in the property (i.e 6 months) before you can serve the notice.
Remember that if you have any questions you can easily ask a lawyer.