What’s the best CPU, motherboard, and RAM combo I can get for under £500?

I'm looking to upgrade my PC, specifically the CPU, and I realize I'll likely need a new motherboard and other components. Right now, I have an RTX 3060 paired with an i3 10100F. Since most of the games I play are CPU-intensive, this upgrade is crucial. I was considering going with a 7800X3D along with a new motherboard, RAM, and CPU cooler. Would this be the best option within a £500 budget? I can stretch my budget a bit and I'm okay with purchasing used parts as long as it's not too risky.