I looked it up, and apparently it’s also called either “cake yeast” or “compressed yeast”. I baked some rolls with it, if I remember right, and you could definitely taste it (which I liked, but some people probably want a “cleaner” taste).

Looks like there are some ways to get it in the UK. I have no clue if the genetics would be similar to what I can get, or what they use in finland.

https://www.forgebakehouse.co.uk/products/fresh-yeast-100g

https://www.shipton-mill.com/products/organic-fresh-yeast