Anywhere you can get steak, jacket potato and salad(ask or dressing on the side)
Grilled/steamed fish, new potatoes and veg (ask for it without butter)
If going to an Italian, go for pasta with a tomato based sauce, or one I had recently was a seared tuna steak and salad
Really it's just getting your thinking cap on, you'll know that cream based sauces, pastry dishes etc will be higher syns
Try not to worry too much, and spoil your trip, just follow your head
Have a good time