Eggs are an easy and quick win, if you want to keep calories low then do a mix of whole eggs and eggs whites. A medium egg white is less than 20 calories and about 5g protein.
I love beef biltong, it’s pricey but the Ember brand is just beef and seasonings its much less processed and messed with than the Jack Links or Kings brand and a 40g pack is 21g protein.
longley farm full fat cottage cheese is bloody brilliant, it’s not the weird sour lumpy stuff you might be used to, it’s creamy, mild and so thick the spoon stands up in it. 100g contains 10.3G protein.
One of my most common meals at the minute is a pack of cooked chicken with salad, it’s quick, easy, low cal and full of protein. I stick to the ‘grown above ground’ rule when it comes to veg as I need to limit carbs due to diabetes so avoid anything starchy. 100g cooked chicken breast is 31g protein, a pack of ASDA flavoured cooked chicken breast gets you about 55g protein in a single meal.
On less ‘surface of the sun’ temperature days I tend to have batch cooked slow cooker meals which are typically 400g lean meat either chicken, pork or beef, a tin of tomatoes, 2 punnets of mushrooms, a bag of sliced onions, half a bag of frozen sliced peppers and whatever seasoning I fancy on the day I cook it. That makes 4 portions each about 250 calories and 27g protein.