With the rise of research impact as a 'third' space (next to research and teaching) within the universities in the United Kingdom and beyond, academics are increasingly expected to not only produce research but also engage in brokering knowledge beyond academia. And yet little is known about the ways in which academics shape their practices in order to respond to these new forms of institutionalised expectations and make sense of knowledge brokering as a form of academic practice. Drawing on 51 qualitative interviews with researchers and research users involved in two large knowledge brokering initiatives in the UK, this study identifies four repertoires of co-production practices: (i) "Challenge" to the existing policy framework, (ii) "Deliberation" between diverse stakeholders, (iii) "Evidence" intervention producing of actionable knowledge, and (iv) "Advocacy" for specific evidence-based options. By exploring knowledge brokering as navigation of different knowledge production regimes -- traditionally academic and policy-oriented -- the paper contributes to the existing debates by providing insights into the nature of navigating science-policy interactions as a process of epistemological bricolage, requiring an assemblage of different meanings, values and practices into new repertoires of practice. Importantly, the choice of a repertoire is not limited to the individual choice of a researcher but rather, it is shaped by the broader institutional context of higher education, risking "instrumental bias" in which practices oriented towards practical solutions are incentivised over critical or participatory forms of engagement.