Every sector has its own accreditations, its own buyers and its own quirks. A cleaning company needs to understand TUPE. An electrician needs current NICEIC registration. An IT supplier should be on G-Cloud before doing anything else.
These sector guides cover what the work actually involves, who buys it, what accreditations you need, typical contract values, how to get started, and the questions small businesses ask most often about winning public sector work in that trade.