Biomolecular simulation aims to provide quantitative, predictive models for molecular structural biology from the level of enzyme catalysis up to cells. Modelling helps us to better understand the information we obtain from our experiments, and can provide insight in situations where experimental information is unavailable. Molecular simulations are based based on well-defined physics, and complement experiments: the unique insight they provide gives molecular level understanding of how biological macromolecules function. Simulations have proved crucial in analysing protein folding and self-assembly, mechanisms of biological catalysis, and the importance of dynamics in biomolecular function. Biomolecular simulations contribute to drug development (e.g. in structure-based drug design and predictions of metabolism) and design of biomimetic catalysts, and in understanding the molecular bases of disease and drug resistance. However, the complexity of biological molecules means that simulating them is extremely challenging, and remains an active areas of research internationally. CCPBioSim is the UK network of researchers that brings together expertise to support biomolecular simulators to perform the best calculations feasible within current scientific understanding and compute resources. We actively engage with the international community of biomolecular simulators, to ensure that the UK has access to the most up to date ideas and insights. We drive methodological developments to improve the state of the art and to integrate biomolecular simulation with emerging experimental tools. We embrace technological improvements that make our simulations faster, more accurate and accessible to a broader community of researchers. We engage with our community by organising conferences and training workshops, and we provide software that makes their simulations less challenging and more effective.