There is a setting in opera://flags for that, but it has some other effects which you may not like. You can try it and turn it back off if the other effects bother you ...
@hugheffo You could be dealing with: a defective Opera installation, a defective user profile, some kind of problem authenticating your particular system's https connection handshaking and transactions with Opera's VPN server, or some kind of connection interference by an over-zealous, onboard antivirus program (including some update made to it). If it were a universal problem caused by Opera's VPN mechanism, these forums by now would be flooded with complaints. There are the occasional 'issue' reports here, but nothing like what would result from a complete, universal VPN failure (plus there's @rtomasz 's earlier report that it's working for him in the UK).
Or... it could involve your local ISP blocking either Opera's VPN IP or an entire block of IPs of which Opera is a part. Sometimes that's done either in error or if there's been formal complaints of copyright violations being routed via those IPs.
There are some things to try in isolating possible "local system" causes. First, with all your antivirus/antimalware programs turned off, try to connect via Opera VPN to a known-safe, low/no-ad website (a speed-test site like https://speedof.me/ or similar should suffice) to see if that affects things. Second, with Opera off, you could backup your profile and try resetting (renaming) it to see if Opera can access its VPN when turned back on. Third, you could try a parallel, portable install of Opera to see if that allows VPN access. Last, if you know somebody in your locale using both Opera and the same ISP, ask them to try the VPN and see what their results are.