I present my work creating mock SNe Ia host galaxy catalogues for TiDES, a spectroscopic follow-up survey for LSST transients and their host galaxies. TiDES has secured a quarter-million fibre hours on 4MOST which will result in the largest ever sample of spectroscopically confirmed SNe Ia to use for high-precision cosmology. I will detail how a sample of this size will revolutionise SNe Ia cosmology and why spectroscopic follow-up of transients is a must in this new era of big-data surveys.