You can, of course, choose to buy a conservatory or orangery from one supplier and then select a different installer to fit them, but this would probably require you to have some higher level of expertise than the average person in order to ensure you are getting the right stuff.
Conservatories are a glass framed building, always featuring a fully glazed roof, and usually built directly onto an exterior wall without integration into the building.
More popular these days are conservatories with solid roofing (How Much to Put a Tiled Roof on a Conservatory?)
Find out more about double glazed uPVC Lean-to Conservatories here: https://www.compareconservatorycost.co.uk/lean-to-conservatory/
Why do housing space standards matter? Without space standards, landlords, housebuilders and property investors get away with providing tiny or inadequate space in their properties. When there is no agreement on what is acceptable as a minimum size for a property, landlords and housebuilders can do as they please.
Fully Fitted Conservatories Cost | Conservatory Price Guide 2018