The first day of school is perfect for these activities:
I really hope these ideas are helpful. I highly recommend to plan at least your first day back BEFORE you go on break, so you are not stressing out during the break and you have plenty of time to rest.
If you do HAVE TO work the Sunday before going back to work I suggest to put it in your calendar for a specific time and only work during that time. Be your most productive self during 1-2 hours of your day and then forget about it!!! (This is why I highly recommend to work in the morning if you can.. just get it out of the way!) I also recommend using the Pomodoro technique, which will help you put all distractions aside.
I'm sure you will be great!!! Don't be too hard on yourself!!