The restrictions include advice that those living in Tier 4 areas should not travel unless it is for a permitted reason.
Tui has cancelled all departures from Luton, which sits in tier 4, from 20-30 December.
It said it would contact clients directly to offer a full refund or the option to amend their booking.
In addition, Tui customers living in Tier 4 due to depart in the next 14 days will be entitled to cancel and receive a full refund or amend for free to any holiday “currently on sale”.
