Student or Learner
We will be sat by the river.
We will be sitting by the river.
i will be staying at
Both are ok, just depends on what you want to say and how you want to express it. Neither is wrong.
We will be sat by the river at noon, waiting for you.
We will be sitting by the river at noon, waiting for you.
A language is a dialect with an army and a navy!
The OP is a student, albeit English; I think that while it is true that both can be heard, 1 is not correct and should not be used in school work.
If someone sits you somewhere, You have been sat there, and you can say "I was sat here". If they're going to do it in future, the OP's first sentence is correct.
One doll to the other doll: Here comes Suzie. We will be sat by the river again!"
I can't think of any other meaning in standard English; and from memory, that was the consensus of the thread about a month or so back.
(I was sat at table G10 for the exam).