The study seems to be about first time having alcohol, but the reporting is equating this with alcohol abuse. I don’t think this is very good reporting at all. Your parents letting you have half a glass of champagne at a cousin’s wedding would seem to count here, but is a wildly different experience to the one implied by this reporting.
I absolutely believe the UK has a youth drinking problem, but I don’t believe this study is necessarily one the media should be pointing to to prove it.