By including composition fluctuations in our dynamical simulation of the time-dependent Landau-Brazovskii model for a diblock copolymer melt we find that disordered micelles form above the order-disorder transition to a BCC phase. At high-temperatures the micelle number density and volume fraction are effectively zero and the melt is disordered at the molecular level. As we lower the temperature the micelle number density increases gradually and approaches the number density in the BCC phase. If we increase the strength of the fluctuations the temperature range over which disordered micelles exist broadens and the onset of BCC order is suppressed. By tracking trajectories we also investigate the dynamical behaviour of individual micelles in an environment of disordered micelles We find diffusive behaviour which we investigate as a function of temperature and micelle volume fraction.