The show The Terror is actually remarkably historically accurate when it comes to the workings of the ships, the backgrounds of the characters, and some of the evidence that has been found. Everything except for the giant ice monsters.

The Erebus and Terror weren't remotely the first ships to be sent on this kind of expedition, so the British Admiralty had plenty of experience provisioning ships where 100+ men might have to survive for years off of what was stocked. They seem fairly roomy on the show, but roughly 2/3 of both ships' space was devoted to storage.

In fact, the fact that they were so confident about their ability to provision the men for that length of time might have been one of the contributing factors in the failure of the expedition- they had left the contract for supplying canned food for the expedition until the last minute, and the company who ended up being hired to provide the thousands of cans of tinned meat and vegetables did a rush job of it. Many of the cans we've found have been discovered to be contaminated with lead from the rushed sealing process.

Here is the total amount of food provisioned for the 124 men of the expedition:

Biscuits

36,487 lbs.

Flour

136,656 lbs.

Pemmican

1,203 lbs.

Beef (salted)

32,224 lbs.

Pork (salted)

32,000 lbs.

Canned meat:

33,289 lbs.

Sugar

23,576 lbs.

Preserved Vegetables

8,900 lbs.

Alcohol (including liquor and wine)

3,884 gals.

Suet

3,052 lbs.

Raisins

1,008 lbs.

Peas

147 bushels

Chocolate

9,450 lbs.

Tea

2,357 lbs.

Concentrated Soup

20,463 pints

Vinegar

1,326 gals.

Barley

2,496 lbs.

Oatmeal

1,350 gals.

Pickles

580 gals.

Cranberries

170 gals.

Everything would be dried or preserved (pickled, canned, dried, or salted). While at sea, fresh water would be stored in casks until they reached the Arctic, and then they would be expected to melt ice for drinking water.

They also carried fresh vegetables and livestock aboard that were meant to be slaughtered over the journey across the Atlantic to get as much fresh food in them as they could before going on the canned rations. And it was expected that they would hunt whenever possible in order to provide fresh meat for the men. They carried weapons aboard to hunt caribou or geese. Crozier was an Arctic veteran and would have some experience doing this.

All these supplies were stored on the orlop deck, and split pretty evenly between the two ships so that if one was lost they wouldn't lose all their food.

There was a kitchen and a cook on board each ship, and the sailor's meals were designed to be varied from day-to-day. Combatting boredom was crucial when overwintering on the ice, and part of that was mixing up your diet. Still, there's only so much you can do with one set of ingredients, so it still would have been pretty monotonous. Officers ate better than enlisted men, and would have dined in the nicer rear areas of the ship off of fine china and cutlery, compared to the more mess-hall-like atmosphere of the common areas, where sailors ate off of sturdy ceramic or earthenware plates.

Breakfast would usually be tea or coffee with ship's biscuits, oatmeal, or fried dough, maybe with jam or butter for the officers. Each sailor would also be given an alotment of tobacco (if desired), liquor, chocolate, and lemon juice (to ward off scurvy). Lunch would likely be more ship's biscuits with tea.

Here's a sample dinner menu from another expedition of the time period:

Monday: Pea soup, boiled salt pork, biscuits. Tuesday: Boiled salt beef, fried dough, plum-duff (a type of suet pudding with cranberries or raisins), biscuits. Wednesday: As on Monday but with stock fish instead of pork. Thursday: As on Monday. Friday: As on Monday but with tinned boiled mutton, rice and biscuits.

Condiments like pepper, mustard, and marinade were also carried on board.