What is a notice to quit?

A notice to quit is the formal way a landlord (or tenant) ends a lodger arrangement or informal periodic tenancy that falls outside the Renters' Rights Act protections - most relevantly, when a lodger rents a room from a resident landlord who lives in the property.

For lodgers: lodgers typically have fewer legal protections than tenants on an Assured Periodic Tenancy, since the Renters' Rights Act primarily covers assured tenancies, not resident-landlord lodger arrangements. A "reasonable" notice period applies - often the length of your rent payment period - but check your specific agreement, as it can sometimes be shorter.

This is exactly why the distinction between being a lodger and a tenant matters so much - the notice rules are genuinely different, and lodgers don't get the same Section 8 protections as assured tenants.