There's lots of other traditional meals to eat in the UK.
Tandoori
Kebab
Curried Goat
Chow Mien
Spaghetti or Pizza
You'll find the Fish & Chips shops have a varied menu these days.
Seriously, there's a great restaurant on The Strand that does Roast Beef, Lamb or Pork. Finding a restaurant that serves food like Steak and Kidney Pie might be tough in London, get out of the big towns and see what's around.
Some English Pubs still do traditional British home cooking. As you get away from London and the cities the menus will change to the regions. Avoid those with a menu that includes foreign foods. They buy it vacuum packed and frozen from huge catering companies and usually taste like crap. Because it is crap.