A saved, dated copy of the official programme page, a written statement of the household's own facts and goals, and a dated file of every third-party communication.
Document the version of the programme you relied on
Because this framework is more recent than the long-established categories, and because what it publishes may be revised, the exact wording a family acted on becomes a fact worth preserving. Keep a copy of the government's page as it stood, with the day it was captured written beside it. Alongside that, keep a plain statement of the family's own circumstances: who each adult is, what citizenship each holds, what deadline is driving the conversation and what has already been promised to an employer, a school or a buyer.
Keep a third note of anybody outside government who has offered help, quoted a figure or requested a payment, with dates. None of this requires legal skill. It simply means that when the household does take advice, the adviser can see in ten minutes what would otherwise take an hour of questions to reconstruct, and any discrepancy between a sales claim and the published text becomes obvious immediately.