I have the misfortune to be summat of a dialect and accent sponge. Four weeks in any region with a strong local accent, and even my wife has difficulty understanding me.
I once had the Nawf Lunnon accent, but now after thirty years it's mostly somewhere between grammar school standard and Kentish.
I den't spend any time in Newcastle or Brum. Imagine it....halfway between Jimmy Nail and Jasper Carrott.