Access to high-quality perimenopause (PMP) care for UK Armed Forces (UKAF) personnel is crucial, given the increasing proportion of women aged 40-55. However, due to the lack of exposure of General Practitioners (GP) to the PMP in Defence Primary Health Care (DPHC), there are concerns about the confidence in PMP management, particularly in prescribing hormone replacement therapy (HRT). To assess the confidence of GPs working in DPHC in the management of the PMP. This study employed a mixed methods approach and included all GPs (Uniformed and Civilian) working in DPHC. A cross-sectional survey gathered quantitative data on demographics, views on perimenopause care, and self-rated confidence levels in managing the perimenopause among Defence GPs. Semi-structured interviews of purposefully sampled respondents was thematically analysed to explore this further. There were 164 responses from 542 Defence GPs (response rate 30.3%). The majority of respondents expressed confidence in managing the perimenopause but reported lower confidence levels in prescribing HRT for younger women and initiating testosterone. Factors influencing confidence included recent perimenopause continuing professional development (CPD), GP gender, and exposure to perimenopause cases. Semi-structured interviews provided deeper insights into GP characteristics, CPD, and awareness of the PMP. Women's health hubs providing PMP care and experiential education were strongly supported. While the study identified gaps in confidence among Defence GPs, particularly in certain aspects of perimenopause management, similar to those found in NHS GPs. CPD and case exposure were important predictors of confidence, with strong support for regional women's health hubs to optimise PMP care. Further research is warranted to explore strategies for bridging confidence gaps and improving perimenopause care delivery within the UKAF context.