A detailed understanding of the progenitors and explosion physics of Type Ia supernovae (SNe Ia) remains a missing link in their use as cosmological probes. This project aims to address two of the fundamental questions that exist about SNe Ia; is there more than one way to make a SN Ia and how does their observed diversity depends on their progenitor systems and host galaxy environments? ESO will play a key role in my project; their expertise, both technical and scientific, will be instrumental in its success. ESO will provide me with many new opportunities to expand my skill set, essential for the development of my research career. I will use SN Ia spectral data to discriminate between potential progenitor scenarios by studying absorption lines from circumstellar material (CSM). Recent studies of CSM have linked SNe Ia in spiral galaxies to the single-degenerate progenitor scenario, but did not study SNe Ia in elliptical galaxies. I will expand this study to elliptical galaxies to determine if the progenitor systems of SNe Ia in young and old stellar populations differ. SNe Ia also display surprising observational diversity that correlates with the properties of their host galaxies. Evidence is mounting towards the possibility that there may be multiple progenitor channels for SNe Ia, and that metallicity may play a fundamental role. Recently, I identified an evolution with redshift in the spectra of SNe Ia, which is consistent with decreasing metallicity with increasing redshift. I will investigate how the spectral and photometric diversity of a large, unbiased sample of low-redshift SNe Ia Ia relate to their host galaxy properties. If the diversity of SNe Ia properties (and hence their progenitor systems) is confirmed to depend on host galaxy metallicity, then this will have major implications for current and future high-redshift SN Ia cosmology surveys, where the SN Ia hosts will be intrinsically low metallicity.