Before you enquire
Make a room-by-room list of the windows and doors you want to change. Take photos and note any draughts, condensation or difficult openings. Rough measurements can help an initial discussion; a professional survey is still needed.
At the survey
Talk through frame styles, colours, glass, ventilation and access. Ask what the quote includes and what work may be needed around the opening.
Before you commit
Check the agreed specification, project schedule, payment terms, warranty and compliance arrangements in writing. Keep the final documentation somewhere safe.