The main goal of the Vera C. Rubin observatory is to perform the 10 year Legacy Survey of Space and Time (LSST). This future state-of-art observatory will open the new window to study billions of galaxies from Local Universe as well as the high redshift objects. To get ready to work with the petabytes of data collected by the LSST we performed a simulation of future observations and uncertainties based on the 50,385 real galaxies within the redshift range 0<z<2.5, from the EN and COSMOS fields of the Herschel Extragalactic Legacy Project (HELP) survey. We obtain the main physical properties of the galaxies (such as SFR, \mstar, and \ldust) using the Code Investigating GALaxy Emission (CIGALE) by modelling their spectral energy distributions. To test the performance of the fit on the LSST observations, we compared the main galaxy physical properties obtained from the SED fitting performed on the real galaxies (with UV to the far-IR coverage) with the one obtained with the simulated LSST optical measurements alone.