From January I would expect, as a true third country, to find our unrestricted movement to European countries somewhat curtailed, which piles yet more pressure on the air travel industry, and the travel sector more widely.
No doubt the likes of Ryanair, TUI and Wizz will be protesting then to their own governments if the EU makes it more difficult to travel just because we are outside the EU. Ryanair has been complaining to the Irish government that there are no countries on the Irish government safe list including the UK. France on the other hand are already giving unrestricted access to the UK for illegal immigrants seeking a dose of the easy life so I don’t expect that to change come 2021