This dataset contains anonymised qualitative data generated during the co-development workshops and subsequent two-phase evaluation of the DeStress-II training intervention. The study utilised the Behaviour Change Wheel (BCW) and Theoretical Domains Framework (TDF) to design an intervention targeting primary care professionals to promote prudent antidepressant prescribing and improve responses to poverty-related mental distress. The data includes notes from the initial multi-stakeholder co-development workshops (comprising GP trainers and community partners with lived experience), alongside transcripts from qualitative feedback interviews with multidisciplinary primary care staff who participated in piloting the expert-led sessions (Phase 1) and the digital, practice-facilitated resource (Phase 2). Complete workshop records and interview transcripts are withheld from public repositories due to confidentiality obligations and ethical constraints regarding sensitive disclosures on socio-economic adversity and mental health. High-level thematic summaries and anonymised supporting excerpts are detailed within the associated publication.