"We'll just have to start using encrypted VPNs, just like they do in other countries with authoritarian regimes"
First, go live in a country with a true authoritarian regime and you'll soon see how lucky the UK is.
Second, do you really think commercial and open source VPNs are not already imperceptible by security services? Actually, no one cares about the security of the data in transit, it's the endpoints that are most relevant. A VPN doesn't hide who you're communicating with.