The Homes (Fitness for Human Habitation) Act 2018 was passed on the 20 December 2018. It starts taking effect three months later from the 20 March 2019. Basically any new tenancy granted after this date, including renewals and statutory periodic tenancies arising, will have to comply with the legislation from the renewal. If the tenancy was running periodic from before 20 March 2019 then you will have to comply with the new rules from 12 months later, i.e. the 20 March 2020. If a fixed term tenancy is running before 20 March 2019 then as long as the fixed term tenancy continues it remains outside of the legislation, regardless of the fixed term (see the next point though). The rules for when this new rule applies very closely mirror the section 11 repairing obligations (and it is, of course, in the same legislation). therefore it does not apply to fixed terms of in excess of seven years, provided the landlord cannot break the fixed term before seven years. Also the landlord is not required to keep fit for human habitation any thing the tenant has damaged, fire, flood etc and things the tenant is entitled to remove from the property.
As the TFP tenancy counts as a fixed term tenancy (based on Goodman v Evely  EWCA Civ 104) this should mean that those on TFP tenancy agreements before 20 March 2019 will have for as long as those agreements last before having to comply.
This will new law will require a landlord to let, and keep a property fit for human habitation (regardless of rent level). In addition to the old list in section 10 of issues that would make a property not fit for human habitation they have now added the 29 HHSRS hazards as reasons for not being fit for human habitation. It is this latter point that causes the most concern as there is no prescribed standard, e.g. it must not have any category one hazards. This means that a landlord will not have any certainty about committing an offence until the judge decides if it is fit or not.
The rules remain unchanged in Wales, meaning effective the fitness for human habitation concept does not apply (due to the very old rent thresholds).
We will be talking about this on our Legal Update 2019 course.