Exchange correlation and spin-orbit interaction (SOI) in 3 monolayer (ML) Co film on clean W(110) surface and on W(110) with 1 and 2 ML Ni buffer layers were studied using low-energy spin-polarized two-electron spectroscopy. Primary electrons with spin projection perpendicular to the scattering plane impinged onto the sample surface and two electrons resulting from a collision of an incident electron with a valence electron of the target are detected in coincidence using position sensitive detectors; with time-of-flight technique for measuring momenta of both electrons. Momentum distributions I(k1, k2) of correlated electron pairs were measured for parallel (I+) and anti-parallel (I-) orientations of the sample majority spin projection and the incident beam polarization at 27 eV primary energy. Energy and parallel to the surface momentum conservations in the scattering event allow us to locate the valence electron involved in the collision within energy-momentum space of the valence band. The measured distributions are presented in the form of asymmetry A = (I+ - I-)/(I+ + I-). The measurements at two opposite magnetizations perpendicular to the scattering plane were performed to map the exchange correlation and spin-orbit interaction in energy-momentum space of the cobalt film valence band. In the binding energy slice of 0.5 eV just below the Fermi level the exchange correlation is maximal in the centre of the Brillouin zone whereas the spin-orbit interaction has maxima at the border of the Brillouin zone. For symmetric detection of correlated electron pairs the asymmetry of the binding energy spectrum represents the spin asymmetry of the Bloch spectral function in the centre of the Brillouin zone. It is demonstrated that the buffer layer of Ni improves the crystallinity of the Co film and enhances the spin asymmetry of the spectral density function by about 30%.