I got information from local pilot about refueling. He wrote me that you can refuel your balloons after the free flight before event on local gas station, which is located near airfield.
The petrol station is open from 6 until 20. Just want to remind you, that this station has no refueling hoses and you need to have your own. Another important thing is that this information isn’t official and if they not refuel your balloon after the flight, me or organisers can’t help you.