Or, like I say above, just manually set your computer clock while watching an accurate time source, like time.is.
This is incredibly simple, really quick (a few seconds) and completely free. No extra gear to buy / assemble / make communicate with the computer etc. I very much doubt you could even connect a GPS module to a laptop or tablet in the time it takes to manually set the computer clock!
The only downside is that you might need to repeat the process if operating for longer than an hour. KISS principles apply.