The UK doesn't need to implement a Great Firewall; if they succeed in convincing service providers to voluntarily exit the UK market, then each service provider

The UK doesn't need to implement a Great Firewall; if they succeed in convincing service providers to voluntarily exit the UK market, then each service provider will block traffic to/from the UK on its own. A few shitty laws may be enough to incentivize the emergence of a Great Patchwork Firewall.