PhDs by Publication are relatively new, but schemes do exist. Generally the previously published work counts towards the PhD, but course work and/or further research still needs to be carried out. As with a PhD by Thesis, the research needs to 'demonstrate an original and significant contribution to knowledge'. A context document or explanatory essay will also need to be submitted (anything from 5000-25000 words). Such degrees are usually only open to people who have a previous association with the university concerned (eg a member of the technical staff).
You should only approach a legitimate university (in the UK any institution with a .ac.uk web address). Beware of institutions which advertise 'Life Experience' PhDs on the internet - if it's not hard work, it won't be worth the paper it's written on.