Small window to double French doors

Planning won't be needed, but building regulations will. To install the set of double french doors you will have to needle prop the external brickwork above the lintel line and also support the internal brickwork and ceiling joists. Form pad stones either end of brickwork where new lintel is to be installed. You can then breakaway the exsiting brickwork down to threshold level. You are then ready to install the double french doors, making sure you have a damp course /membrane under the threshold cill.

Contact Building Control to inform them of the works that you shall be doing. Temporary works will be needed to support the load above your old window and to also allow a structural lintel to be placed above where your new doors are going to go. Once this is done demolition can begin beneath the temporary works. Planning permission is not needed for this job unless it is a listed building.