You are comparing apples and oranges.
The UK Government Data I have linked is based on adults of working age (16-64), as I clearly stated in my post.
The EU data you have linked defines economically inactive as anyone outside the workforce, including infants, children, pensioners etc.
https://ec.europa.eu/eurostat/statistics-explained/index.php?title=Glossary:People_outside_the_labour_force
Comparing ‘unemployed data’ is a little more problematic as each nation and indeed different governments within each nation defines unemployment differently.
By example, the UK data I have linked is based on adults between the ages 16-64 whereas the EU data you have linked is based on individuals between the ages 15-74.
https://ec.europa.eu/eurostat/statistics-explained/index.php?title=Glossary:Unemployment