I cannot recall an example where a breach of such guidance in-and-of-itself is an offence: it's when the underlying legislation is contravened that one is committed.
Note that the cited article say this:
this guidance is of a general nature. Employers should consider the specific conditions of each individual place of work and comply with all applicable legislation and regulations, including the Health and Safety at Work etc. Act 1974. This guidance does not supersede existing legislation or regulations across the UK
More broadly, and away from the NHS, the relationship between guidance and statute was examined in The Financial Conduct Authority (FCA) v Arch Insurance (UK) Ltd & Ors  EWHC 2448 (Comm) where adherence to social distancing measures impacted on safe working practices on building sites, causing delays and an increase in costs. The court determined that:
It follows that government advice or recommendations, whether before or after either set of Regulations came into effect, cannot have imposed or ordered a denial of access or a hindrance in access, however strongly worded the advice or recommendations were, since they did not have the force of law.