When choosing a UK casino with a solid slot library, look for clear RTP info...

https://papa-wiki.win/index.php/RTP_vs_Volatility_-_Which_Matters_More_for_a_Casual_Player%3F

When choosing a UK casino with a solid slot library, look for clear RTP info since RTP reflects long-term payout averages. Some slots have varying RTP versions depending on the operator