Despite all the nonsense that's posted about UK on the internet, British agencies do require a warrant to enter your home. TSA on the other hand does not require a court order to confiscate and mirror your device before giving it back to you.
Edit: Just to be perfectly clear - Border Force in the UK can do the exact same thing to you once you return, British citizen or not. Leaving your device at home is still the safest choice.
Despite all the nonsense that's posted about UK on the internet, British agencies do require a warrant to enter your home. TSA on the other hand does not require a court order to confiscate and mirror your device before giving it back to you.
Edit: Just to be perfectly clear - Border Force in the UK can do the exact same thing to you once you return, British citizen or not. Leaving your device at home is still the safest choice.