"Call me Hagrid," he said, "everyone does. An' like I told yeh, I'm Keeper of Keys at Hogwarts -- yeh'll know all about Hogwarts, o' course.
"Er -- no," said Harry.
Hagrid looked shocked.
"Sorry," Harry said quickly.
"Sorry?" barked Hagrid, turning to stare at the Dursleys, who shrank back into the shadows. "It's them as should be sorry! I knew yeh weren't gettin' yer letters but I never thought yeh wouldn't even know abou' Hogwarts, fer cryin' out loud! Did yeh never wonder where yet parents learned it all?"
(Harry Potter and the Sorcerer's Stone)
It’s not like ‘yeh’ll’ is a future tense, because of the next reply, ‘no.’ So it seems a dialect for ‘you all’ or ‘you already’ ,etc. What does the pronunciation imply?