(2-part post):
There are two different documents involved here.
For a landlord to terminate your brother's tenancy, the first stage is that he should have served a 'notice to quit'. This is simply a formal letter from him, to your brother, stating when the tenancy will come to an end. (If the tenancy is a 'rolling' one, the landlord would normally have to give the required notice but not state a reason. Otherwise, in order to terminate a tenancy before it would normally come to an end, the landlord would have to give a reason).
Since the 'notice to quit' is a simple letter from the landlord, the only person who will have a copy of it is the landlord. So, unless he's prepared to provide a copy of it, you can't get hold of one directly, however . . .
If your brother has ignored a notice to quit, the second stage is that the landlord would 'apply for possession' to the County Court. If this happens, the court will write to your brother. The documents which the court sends should outline the landlord's case, so this should effectively reproduce the contents of the notice to quit. It's these court documents which your brother should take to a solicitor.
It's not unusual that a court will first set a date, then write to the tenant. So, if the landlord was present when the date was set, he could well know about it before your brother receives anything in writing.