Next step would be requiring UK ISPs to block traffic to the VPNs. They’ve already made it so you can’t go to some sites based on DNS lookups, so there’s precedent. Making it by IP address from a continuously-updated list would make it exceedingly difficult for regular users to access a public VPN, and while making one yourself from a VPS is straightforward, it can get expensive very quickly if you want to watch videos or download lots of stuff through it.