I think you’re correct Awaywego, there’s nothing in the rules preventing it unless there’s something in the National League Handbook which gets referenced in the rules but I can’t find it online. I reckon they could start selling after Saturday.
I guess the thing is at the moment, as it stands, if Brackley win their last game and we lose at Gloucester and the goal difference is overtaken then we would finish third. Obviously highly unlikely but I can see why the season has to end officially before tickets can be sold.