In all honesty you don't sound like you have a clue about proper nutrition.
It's not uncommon desu,
Protein, carbohydrates and fats should all be consumed from a variety of sources, as well as plenty of fruits and veggies.
For protein look into;
Eggs
Meats
Milk
Beans (combine with rice)
Carbs look to;
Rice (white or brown, there's no difference)
Oats
Potatoes (sweet or white)
Bread and wheat
Grains, lentils etc..
Fats;
Butter (not spread, too much veg oil)
Whole milk
Olive oil
Avocados
Coconut oil
Nuts
Fats from meat
Oily fish (mackerel, trout, salmon)
Veg and fruit are key to a proper diet imo, and can be fresh, tinned, dried etc.. you might not be able to have fresh fruit every day but some now and then is essential. Frozen bags of mixed veg are cheap, very easy to prepare and go with pretty much everything.
As to the cheapest protein then actually unflavored whey or some other supplement probably works out to be the cheapest per 100g. However Aldi and Lidl sell 10 large eggs for £1 a box, that's the best deal you'll find on them short of going to a wholesale and buying in serious bulk.
Look into the bargains section of asda etc... you can get a large pork joint for £5 now and then. I slow cook this and it lasts probably 5 meals.
Rice is cheap, however if you can spare it I really reccomend buying those quick cook boil in the bag types. Lidl sell a box of 8 for about £1.50. Much cheaper than buying micro rice and it's perfect every time. Easy to record if your counting too.
Butchers sell 5kg of good quality chicken breast for £20, however now and then some supermarkets will have it on special that'll come to slightly less.
Don't overlook chicken thigs and legs etc.. if you want to reduce the fat remove the skin. Frozen meat can often work out cheaper than fresh. Oats are cheap from anywhere really.
Research a bit more lad, nutrition everything here and you can't half ass it. Eat, rest, train. In that order of importance.
