One tweak to the rules and all of a sudden not only do porn sites have to verify the age of their UK visitors but also anyone connecting from something other than a residential ISP.
The more troubling thing about these laws is enforcement. The threat of fines only works against websites that map to a business entity. For anything else there will surely see a ramp up in the size of The Great British Firewall Ruleset, edited by the courts, and distributed to the Big N (5?) ISPs.
What will become of the smaller ISPs that refuse to block illegal sites?
Which sounds like a silly question ("of course the marketing is BS") but why even bother marketing if the core value proposition of your billed-monthly service doesn't work? Seems like a waste of money since you'll at most get people for one month when they cancel after realizing they can't watch Canadian Netflix from Florida, or whatever.
There are alternatives like Hola VPN, a "free" peer to peer VPN except non-paying users have traffic routed through them. But performance of peer to peer VPNs are not as good.