I think a fake Patek Nautilus, for most people, is going to be rather obviously fake - I mean your friends/colleagues likely know if you're a multi-millionaire or not.
If you're an ordinary accountant, solicitor or IT person, living in your 4 bed Barratt home, with your PPI basic model BMW sat on the drive, leather corner sofa from the DFS sale, "art" from Ikea and a "Live, Laugh Love" sign on the wall etc.. then let's be realistic, you're not dropping 80k on a watch!
A Rolex or Omega might be a tad more realistic perhaps, though still quite an expensive purchase.
Though really, given that the high-quality fake versions of stuff like that Patek can run into several hundred £s themselves, might as well get a real watch you can afford like a Nomos or a Stowa - something well made, actually looks good and isn't fake.