I use the vanilla Optimum Nutrition whey protein powder every day for a breakfast smoothie. I keep it really simple. I mix the powder with water and then add frozen fruit. Aldi has a really good selection of frozen fruit, including some protein ones that contain flax or chia for an extra protein boost. My personal favourite is the mango and passion fruit gut health one, but all of their frozen fruit mixes are good and very reasonably priced.
I have the chocolate Optimum Nutrition whey powder too but I really only have that as a milkshake. I bought them from Amazon as it was the best price, even compared to the ON website.
I have some clear protein powders too but I don't really enjoy them. Something about them tastes 'heavy' to me. I've tried MyProtein vimto and cranberry/raspberry. Also Optimum Nutrition apple/raspberry. They do taste nice but I don't prefer them.
Food wise, yoghurts are a good choice. Aldi sell some really thick protein ones made from Quark, or Lidl do some that are more like normal yoghurt texture. Greek yoghurt and skyr are great too, also from Aldi. Lastly, Aldi sells really nice chocolate protein mousse and the Lidl lemon protein mousse is dreamy. I've tried protein pudding but I'm not a fan of the texture (a bit like blancmange).
I quite often have a babybel, mini cheddar stick or a small chunk of cheese if I'm peckish. Fridge raiders (or the Aldi own brand) or deli meats like ham or sliced chicken are an option too.
I'm not normally an Aldi shopper (it's not that close to me) but they really do have the best yoghurt and frozen fruit selection of any of the supermarkets IMO. They also have their own 'protein' range of products. It might just be marketing but it makes it easy when shopping 🤷♀️