My firm has effectively banned all non-essential work travel until mid-April. In terms of personal travel it remains at our discretion but we're asked to be mindful of changing circumstances that could result in issues at international borders or result in us having to self-quarantine upon our return or otherwise "cause a disruption" (whatever that means)!
I don't have any personal travel until the latter half of April so we'll see what happens then but I think it would be very difficult for any employer to try and restrict what its employees do in their own time. That said, however, if a Government was to impose travel restrictions (such as in Italy for example) then that would be a different matter.