Overspill-era housing
If your Witham house was built between roughly 1955 and 1985, the materials worth checking before any work are ceiling and wall coatings, the floor covering under later laminate or vinyl, panelling around the boiler or airing cupboard, soffits, and the garage roof. None of those can be identified reliably by eye.
For a straightforward renovation, a refurbishment survey limited to the rooms being worked on is usually enough, and costs considerably less than a whole-house intrusive survey.
