The correlation between 21cm fluctuations and galaxies is sensitive to the astrophysical properties of the galaxies that drove reionization. Thus, detailed measurements of the cross-power spectrum and its evolution could provide a powerful measurement both of the properties of early galaxies and the process of reionization. We will present the evolution of the cross-power spectrum between 21cm emission and galaxies using a model which combines the hierarchical galaxy formation model GALFORM implemented within the Millennium-II dark matter simulation, with a semi-numerical scheme to describe the resulting ionization structure. We will also show predicted observational uncertainties of the cross-correlation coefficient based on specifications of the Murchison Widefield Array combined with galaxy surveys of varying area and depth.