I know just 2 examples of "British" food : Irish stew and Haggis, traditional Scottish dish.
Irish stew (in Irish Stobhach Gaelach) is a traditional Irish dish made from lamb or mutton, (mutton is used as it comes from less tender sheep over a year old and is fattier and more flavourful) as well as potatoes, onions, and parsley.
There are many recipes of Haggis, most of which have in common the following ingredients: sheep's 'pluck' (heart, liver and lungs), minced with onion, oatmeal, suet, spices, and salt, mixed with stock, and traditionally boiled in the animal's stomach for approximately three hours.
My friends from GB told be it's worth to try both. I agree for the Irish stew, we cook it often at home. But Haggis ? It's not "my cup of tea", as we say in French .
Old bob