  Cosmic rays can penetrate planetary atmospheres driving the formation of
prebiotic molecules, which are important for the origin of life. We calculate
the Galactic cosmic ray fluxes in the habitable zone of five nearby,
well-studied solar-type stars and at the orbits of 2 known exoplanets. We model
the propagation of Galactic cosmic rays through the stellar winds using a
combined 1.5D stellar wind and 1D cosmic ray transport model. We find that the
habitable zone of 61 Cyg A has comparable Galactic cosmic ray fluxes to
present-day Earth values. For the other four systems ($\epsilon$ Eri,
$\epsilon$ Ind, $\xi$ Boo B and $\pi^1$ UMa), the fluxes are orders of
magnitude smaller than Earth values. Thus, it is unlikely that any as-of-yet
undetected Earth-like planets in their habitable zones would receive a higher
radiation dose than is received on Earth. $\epsilon\,$Ind$\,$b, a Jupiter-like
planet orbiting at $\sim$11au, receives higher Galactic cosmic ray fluxes than
Earth. We find the suppression of Galactic cosmic rays is influenced by whether
diffusion or advection dominates at GeV energies and at distances where the
wind has reached its' terminal velocity. For advectively-dominated winds
($\sim$younger systems), varying the astrospheric size influences the
suppression significantly. For diffusion-dominated systems ($\sim$older
systems) the astrospheric size, and therefore knowledge of the ISM properties,
are not very important. This reduces the Galactic cosmic ray flux uncertainties
in the habitable zone for diffusion-dominated systems. Whether a system is
advection- or diffusion-dominated can be determined from the stellar wind
properties.
