If your glasses fog up then your mask is not working properly, I'm afraid. Fogging glasses mean that there is an escape of your breath around the top of the mask. So your aerosols can get out, and, presumably everyone else's can get in... Mask must fit snugly round the bridge of the nose and across the cheekbones. So you have to experiment with various masks to get ones that fit snugly.
Visors are useless (as are, incidentally, plastic screens in shops etc) All they do is deflect the aerosols to the bottom or sides where they then make their way freely into to air around you. And they'll let them in, too.
Of course, I hope that you will be covid free when you travel, esspee, as will, I hope, your fellow passengers. But if I were doing a long flight I'd want to be sure that the mask protected in both directions.