The family of guanadinium metal formates (M=Mn, Fe, Co, Ni, Cu) are isostructural with the perovskites and are therefore of interest for potential applications: in particular, the polar Cu complex is believed to be multiferroic. Each of these materials has been reported to exhibit canted antiferromagnetism, with the Cu compound displaying 1D interactions along a chain of short bonds in its Jahn-Teller distorted coordination geometry. Nonetheless, the magnetic structures of these compounds have not yet been directly observed. We propose a high-resolution magnetic neutron scattering study of the atomic and magnetic structures across their magnetic transitions, to characterise their magnetic behaviour, including spin canting and the dimensionality of the magnetic interactions, and in particular the influence of the Jahn-Teller distortion in the Cu compound.