Need help repairing a leaking toilet flush

Hi, I have a toilet in my bathroom that has a leaking flush mechanism. It’s constantly running water and I’d like someone experienced to come and fix it properly. The flush handle feels a bit loose and the water keeps running even after flushing. Ideally, I’d like the repair done quickly as the noise is quite annoying. Please bring any necessary tools or replacement parts if possible. Looking forward to getting this sorted soon!