If the UK is going to require adult verification it should be built into your internet contract. Yeah, I'm an adult. I'm paying my bills, of course I'm a fucking adult. I over pay for this garbage internet.
Uploading a selfie? The ai is going to determine if you're over 18? Can the ai determine if the selfie is also ai?
Parental controls exist. Why should single adults be forced to jump through hoops because most parents are lazy fucks who don't take responsibility for their kids?