Hi there, i fit a lot of velux windows, i can change the glass or can replace the whole unit without the need for scaffolding,there will always be a little damage to the plaster reveal but this can be rectified easily & cheaply, please call me or text for more more details, i have photos of work carried out plus testimonials, thanks,,, Phil @ TOPNOTCH PROPERTY SOLUTIONS, FULLY INSURED FOR PIECE OF MIND !!