Ask HN: How best to sell BTC in a private wallet?

I was lucky enough to buy about 4 Bitcoins ten years ago on IRC, long before crypto exchanges were really a thing.

Over the last couple of years I've thought about cashing out. I've not really followed cryptocurrencies since I bought them, and so I've got no idea how best to liquidate them.

They're held in a private wallet, on a USB stick, in an envelope in a drawer.

What would be the best way of turning them into real money (British Pounds Sterling, I'm in the UK) without getting scammed?