Whatever the frequency of payment, it must be specified in a written statement of particulars, which must be given to employees within a month of starting work. (From April 2020, this statement must be given to all workers from the first day on the job.)
You should be told of any change in when or how frequently you will be paid (e.g. monthly, weekly, etc.) within one month of the change.
It is a fundamental (very serious) breach of the employment contract not to pay wages on time.