I'm not convinced the protein in the Aubrey Organics would do anything, full size protein won't absorb and little to nothing will stick since the molecules are too large.
THE NATURAL HAVEN: Size matters : Protein Conditioning (part 1 of 2)
I think they do ship to Europe but it's pricey, other wise British Curlies stock Komaza Care. I wasn't saying you need to purchase from them tho, I don't see why you can't combine a weak gelatin treatment with a product containing behentrimonium and aloe to hopefully avoid build up and dryness.
If you are in Europe the other option for hydrolysed protein on the cheap is Schwarzkopf Gliss (Kur) Ultimate Volume conditioner. The lovely Neleke
and I are both using this. Ingredients
"water, cetearyl alcohol, hydrolyzed collagen, panthenol, cocodimonium hydroxypropyl hydrolyzed keratin, hydrolyzed keratin, isopropyl myristate, behonoyl PG-trimonium chloride, citric acid, VP/VA copolymer, phenoxyethanol, behentrimonium chloride, sodium methylparaben, hexylene glycol, fragrance, polyquaternium-37, dicaprylyl carbonate, hexyl cinnamal, amyl cinnamal, limonene, linalool, benzyl salicylate
2a-2c, medium texture, porous/ colour treated. Three years CG, growing out mechanical and chemical damage = breakage and very high porosity. Past armpit length heading for waist.
CO-wash: Inecto coconut
Treatments: Komaza Matani, coconut oil, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss ultimate volume, Inecto argan
Styler: Umberto Giannini jelly, Boots Essentials gel
Experimenting with: going back to basics