I want to understand how modern online casinos integrate payment systems in the UK. Are there any platforms that already have ready-made solutions for secure transactions and financial flow analytics?

I can recommend checking out https://www.soft2bet.pro/. Provides detailed descriptions of modules that help integrate payment systems and control financial flows in accordance with UKGC standards. This is convenient for operators who want to quickly launch a casino or bookmaker platform without spending years developing their own infrastructure. The platform also offers analytics tools to monitor risks and player behavior.