There are a number of indicators for where someone is from that might be visible to site operators, far beyond a simple IP address. You could try an incognito window (because cookies), as well as changing your region settings.

Beyond that, try spinning up a VM (VMware has a free version, as do many others). Install a fresh OS on it, always pretending to be in whatever your destination country is. Install the (e.g) UK keyboard, select a UK timezone, etc. Install your VPN right away, before opening a browser.