Woodworm in furniture can be cured by application of proprietary woodworm killer. Coat all surfaces, polished and unpolished, and inject fluid into a few flight holes with a special injector. As a precaution against woodworm, you can buy an insecticidal polish.
Woodworm in structural timbers can be treated on a do-it-yourself basis, and the proprietary fluids used by the experts are available from builders’ merchants. All timbers must be cleaned down first, and any roof insulation material will have to be removed temporarily so that you can get at the joists to work on them. Also, this avoids the fire-risk of insulation becoming impregnated with the fluid or small polystyrene granules dissolving together.