Need a quick repair for a leaking toilet flush in UK home

I'm looking for a reliable handyman to fix a leaking or faulty toilet flush in my UK home. The issue started gradually and now the flush doesn’t reset properly, causing running water and wasted water. Ideally, the job involves diagnosing whether the fill valve, flapper, or flush mechanism needs replacement and completing the repair on the same visit. Please bring appropriate replacement parts, such as a compatible fill valve or flapper, and test for leaks after repair. I prefer a tidy, professional approach, with minimal noise and disruption. Light access to the bathroom is available during the day, and I’m hoping for a same-day or next-day appointment if possible.