A few thoughts, ...Catherine is woken by the housemaid opening the shutters at 8 am so breakfast may've been taken at the abbey at a relatively early time of 9 am.

We have a few details- in Ch. 25 in the morning, the General is 'between his cocoa and his newspaper'. I believe cocoa was a very fashionable beverage.

Mrs Austen in 1806, described the splendors of a Stoneleigh Abbey breakfast-perhaps similar to what Catherine knew-
Chocolate, Coffee (both taken by General T), and Tea, Plumb Cake, Pound Cake, Hot Rolls, Bread, Butter, and 'dry Toast'.

Possibly, there were hardboiled eggs and fresh cheeses as well.

Georgian breakfasts were lighter meals with varieties of breads, cakes and hot drinks.
Apparently the French bread was like a brioche, a soft, yellow roll made by enriching the dough with butter, milk or eggs.
It was the most highly regarded bread of the C18th,
(more flavoursome than white bread).

We know General Tilney's hobby horse was his garden and hot house fruits. Genteel households made preserves & jellies.
One of Julie's L&T posts on pineapples mentioned pineapple marmalade- sounds quite fancy !
The breakfast table may've included a number of fruit preserves and jams presented on silver dishes for the breads.
Perhaps silver urns for hot water and coffee, on the sideboard.
In accordance with General T's idea of 'encouraging the manufacture of his country', the breakfast set is probaby Wedgewood.

At the abbey, Catherine was likely introduced to foods she was not familar with.
So she may've been abit bewildered the first few mornings by the array of gourmet foods before her- Chocolate for breakfast !
Henry may've helped her in her choice of food, passed plates to her -and advise she 'try the French bread' ;)
(Maybe why she talked of the French bread at home ? )
If General T. wasn't present, Henry may've dismissed any
footmen and enjoyed serving the coffee to Catherine & Eleanor.