The Time-Domain Extragalactic Survey (TiDES) is an upcoming spectroscopic follow-up survey for LSST transients and their host galaxies. Having secured a quarter-million fibre hours on 4MOST, TiDES will gather the largest ever sample of spectroscopically confirmed Type Ia supernovae (SNe Ia) to use for high precision cosmological measurements. In this talk I will present how current surveys such as the Dark Energy Survey are using SNe Ia for precision cosmology, give an overview of TiDES and our survey aims, as well as detailing ongoing work into creating a dynamic mock catalogue of TiDES SNe Ia and their host galaxies.