Those rules would only apply to VPN providers in the UK, so the whole mechanism would be pointless.

They could start whitelisting money / credit card transfers, I guess. However, reputable VPN providers already accept envelopes full of cash and crypto, so I guess the UK would need to start reading all international mail, and block crypto.

At that point, people could just use tor to bootstrap the VPN account + payments.

History says teenagers will figure this stuff out before adults (due to infinite free time and infinite bragging rights for knowing how to do it).