As you know, I am in the US, not in Europe. I have looked around this morning on the internet and discovered that a few years ago pellets were available in Europe. Then breeders over there began to see a decline in the number of babies produced. They stopped using pelleted foods and went back to the "old ways" of feeding a mixture of seeds, lots of freshly prepared food with small amounts of supplements sprinkled on top, and production increased.
A good basic diet for birds, if pellets aren't available, is to cook brown rice and beans to make a complete protein. Then add fresh or thawed frozen mixed veggies and green leafy veggies plus a small amount of fresh fruit. You do have to add a vitamin mineral supplement made for birds to this mixture. I cannot tell you the amounts, but most vitamin/mineral containers have dosages listed.
I cook large amounts of rice and beans and store them separately in my freezer. Thaw and mix small amounts together, then add the fresh foods and serve.
You have eggfoods made in Europe that I used years ago when I was breeding Lady Gouldian finches. One was Quiko and another was CeDe. There are others, too. My babies were large and very healthy.
You do need to study up on how to feed it. Vitamin supplements are used less than if no eggfood is fed.
I found an online catalog at JungleGoldLimited.com Lots of products for birds in Europe. Many that you won't need but nice to see what is available.
Other members may know of other places for you to look.
Annie