UK border cops can seize and retail all your data without suspicion or charge

And you aren’t hard encoding your disk drive with something like LUKS… why? Being able to seize it, and being able to access it (without a serious effort), can be made separate issues.

(Yes, given time, any simple crypto can be broken. But you don’t need perfect security; you just need security good enough that the cost of breaking it exceeds the value of the contents. Just as you don’t need pick-proof locks, you just need locks that are good enough that any burglar goes elsewhere.)

((Admittedly, my personal laptop is not yet encrypted. But I don’t travel with it; it’s really a compact desktop with built-in UPS that I can carry around the house if I need to. My work machine is hardened.))