I have no idea what is in the UK, but there are some things worth noting. Protein powder in notorious for being less pure than it should be. Heavy metal contaminants are a big issue as well as added off label performance compounds. Even at the recommendation of another athlete, one would still be wise to do their own research regarding what they are putting into their body. With that said, I have found 4 brands that seem pretty clean and clear of any contaminants or other nefarious additives.
https://www.amazon.com/gp/product/B0025PZQ0M/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B01JNUHA5A/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0787S4YN1/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0017OFTQS/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1
Good luck and good riding!!