I plan to take this trip in June. Any 'do's or don'ts' would be appreciated.
If you can try and get a train to Avignon-Centre station rather than Avignon TGV: the TGV station is a bit out of town although shuttle buses meet the trains.
For detailed timetables use the German Rail site, www.bahn.de. Click on the drop-down flag menu for English. After you get summary timetables for Barcelona-Avignon, click on the arrow to the left of each departure time to see the connecting points.