Brits: What kind of cheese and pickles in a pickle and cheese sandwich that I'm always reading about? What is 'black pudding'?

Usually fairly basic Cheddar cheese in a sandwich, along with Branston Pickle or similar.  Note spelling of Branston.

Cheddar cheese and Branstone Pickles

and Black Pudding is a Blood Pudding  great with eggs Bacon and Toast for breakfast

Cheese and Branston Pickle is a cheese ploughmans or cheese and pickle sandwich. Black pudding has blood in it. White pudding does not

There is no set cheese and pickle in a cheese and pickle sandwich. It's more correctly called cheese and chutney.

Black pudding is a blood sausage made of pork, oats, pork fat and pig blood with plenty of seasoning.

cheese

Not sure about the weird looking pickle

The cheese is cheddar

Black pudding is dried blood of pigs

https://bringoutthebranston.co.uk/about/history/

The Cheese & Pickle sandwich is made with Cheddar cheese and Branston pickle.

Black pudding is made from pigs blood, fat and oatmeal, in a sausage.