One of my favorite resources for Advent, or any day, is Pray as You Go. I use the app, and you also can access the resources through this website.
This season, Pray as You Go is offering a “New Beginnings Advent Retreat,” with additional Advent material in the daily prayers on the home page and the “Living the Magnificat” imaginative prayer exercise found on the “Going Deeper” section.
As the website says, Jesuit Media Initiatives of the United Kingdom produces the web site with material written by a number of Jesuits and experts in the spirituality of St. Ignatius. Check it out!