It's haddock in NE England too, but cod, plaice and various others - skate is a speciality of one of the best Tyneside places - are also common (ish). Portion size varies enormously, as does the greasiness (or otherwise) of the meal.
Battered sausages, large or small, curry sauce with chips, all sorts of things are possible, particularly now many chip shops are run by persons of other origin than English. Doner kebab and chips is not uncommon for this reason, particularly where there's only one outlet in the vicinity serving pizza, kebabs, fish & chips - the lot.

I'm sure there's a study there for some enterprising catering student or sociologist - the relative densities of these outlets in various types of areas (neighbourhoods) and the relative quality / tastiness / menu of the products.
Final year project and free meals with it,

What could be better?

Paws