I’m definitely not low-carb
but here are some ideas:
Soya-based vegan meat alternatives such as burgers, meatballs - could have with zucchini noodles or something if that’s your thing,
Vegan soya chicken (Naked Glory, M&S, Iceland, ASDA), fry it up in some olive oil with some nice herbs and spices and chuck it in a nice salad
Tofu - cube and pat dry, then fry in olive oil and add some soy sauce/seasonings of choice, add to a nice veg stir fry
Seitan - can be expensive/tricky to find (you can also make it very cheaply at home) but you could try the Granovita tinned mock duck from Holland & Barrett/ASDA in a stir fry or something
There are quite a few low carb vegan protein bars around nowadays (eg the MyProtein/MyVegan vegan carb crushers, or Missfits brand protein bars) although I tend to steer clear of sweeteners because they upset my stomach a bit - if this isn’t the case for you, might be worth giving them a go. Similarly, if you can stand protein powder there are lots of vegan protein powders around nowadays (again MyProtein or MyVegan are good places to order and they usually have some kind of discount code going)
So you could do something like:
Breakfast: Protein shake + protein bar OR Protein shake + scrambled tofu and veggies (mash 1/2 a block of tofu with a fork, add a splash of soy sauce, some garlic powder, paprika, turmeric etc. Fry some very finely diced pepper, onion, mushroom in some olive oil then add the tofu. Could also add some vegan sausages - Richmond meat-free or Linda McCartney ones are nice
Lunch: Peri-peri (or similar) soya chicken in a nice salad
Dinner: tofu or seitan stir-fried with loads of veggies in a tasty sauce
Snacks: protein bars/a few nuts/veggie sticks
Hope that helps!