I think you have to try to find things that you enjoy for all your meals, otherwise you'll be tempted by other stuff, particularly if you have to take a packed lunch to work. I work close to a supermarket - if I've brought something into the office that I don't really want / doesn't appeal by about 11.30am, and my motivation / discipline is waning, I'll just go to the supermarket at lunchtime and get something I fancy.
I do try to mix it up - for me, I'd get bored eating the same things. So here are my options (I'm trying to keep cals to 1000 per day).
Breakfasts
Egg muffins (homemade - make six or so and freeze, then take one out of freezer day before, microwave at home/work - fry off onion, mushroom, pepper, spinach, turkey rashers, add beaten eggs, tiny bit of cheese on top, cook in muffin cases)
Fresh / frozen fruit with a dollop of FF greek youghurt, sprinkling of seeds
Pancakes - just a banana & 2 eggs blended and cooked like pancakes - drizzled with honey or Jim James no added sugar chocolate/hazelnut spread
Occasionally a crumpet / bagel thin or oats if I'm running that day
At least 2 coffees with skimmed milk
I don't snack, but if I plan to run (when I say run, I mean a 3 mile jog) I'll have something about 11am if I run at lunchtime, or about 4pm if I'm running after work - usually humous & carrots or one of the egg muffins)
Lunch
Humous and carrot sticks, protein yoghurt
Chicken salad with spicy mayo
Ham / Chicken / Egg mayo wrap (I buy the free-from ones, about 80 cals each) with loads of salad, or half a soft pitta pocket
Warm Feta & roasted veg salad
Homemade soups
Stuffed peppers
Dinner
Family dinners but changed slightly - e.g. spag bol / tacos etc but served in a lettuce leaf rather than with rice / taco shell.
Home made lamb doner kebab in half a soft pitta
Curry (either veggie / chichen) with more veg rather than rice
Chicken fajitas with low cal wrap as above
Burger bowl (3% skinny burger (M&S/Sainsburys) with all the burger trimmings but without the bread roll)
Heck chicken sausages with veg
Baked feta / Halloumi with tomatoes / roasted veg over broccoli / greens
Chicken stir fry with bare naked noodles
Omelette if I've not had eggs for other meals
Roast dinner
Chicken stuffed with philadelphia / wrapped in bacon medallions with veg
Falafel with veg / salad
Chicken Ramen
Occasionally supermarket bought ready meal
Stuffed butternut squash with roasted veg and pine nuts
Salmon fillet (maybe with pesto / asian glaze) with roasted veg / salad
Tea / decaf coffee during day, skimmed milk. Lots of water.