Interesting! Does this mean that you can focus on publishing a few papers and make a proposal highlighting all your contributions and papers, then apply to get a PhD title.
Nope, you still formally sign up like a standard PhD student but will organize your thesis as a series of published and peer-reviewed papers, instead of the standard format, at the normal end of your PhD program. There is neither an accelerated path nor a diy option because the PhD is strictly meant as training time in the UK, much more like an apprenticeship than autonomous contribution.