YOU READ IT YOU MORON!!!
It can be served 4 months from the tenancy start.
"You cannot use a Section 21 notice if any of the following apply:"
"it’s less than 4 months since the tenancy started, *or the fixed term has not ended, *unless there’s a clause in the contract which allows you to do this"
There are many, many, many, many, many clauses in AST's that allow a landlord to serve a section 21 before the end of the fixed term if you breach them.
And the landlord could just say that you consistently smoke weed which is a breach.
bingo bango, you are evicted.
you are very wrong in that there can't be swift consequences and are giving out dangerous advice to people.