Yes, it’s 100% legal. There are no laws in London or the wider UK that stop you from using a VPN to protect your digital privacy. In fact, given the UK's
Investigatory Powers Act 2016 (which lets ISPs track your history), it’s actually a pretty smart move. Just a reminder: if you do something illegal while connected, it’s still illegal. The VPN is for security, not for being a digital outlaw.