Many social science departments in EU/UK recommend getting in touch with potential supervisors first before submitting a formal application which involves a proposal. Should the applicant approach them with a proposal already (very) specifically written? Or just broadly stating research interests and the intended project scope for the next few years?
Is the PhD proposal supposed to be well-prepared before initial contact with potential supervisors, or agreed and finalized after consultation and discussion to fit both parties' interests?
I understand that academics get many emails from potential students, so I wouldn't imagine they'd like to read through everyone's proposals. This question is informed by other posts like this, this, and this - but most relevant discussions I see here on SE are either quite specific to the science/engineering community or North American system, and I'd like to hear about what is the expected pre-application communication in UK and EU, and/or in other disciplines, especially in social science.