Need a plumber to repair a faulty toilet flush mechanism

I'm looking for a reliable tradesperson to fix my toilet flush. The unit leaks occasionally and the flush doesn’t fully clear the bowl. I suspect the fill valve or flapper may need replacement. The job is in a residential apartment in Ireland, please confirm compatibility with standard UK/Ireland toilets. I’d prefer a tidy execution, arrive with basic tools, and provide a quick explanation of the issue and the solution. Ideally completed in one visit. Please specify material costs if replacements are needed and any access requirements.