I believe a pacemaker
has little, even no, effect on Atrial
Flutter or Fibrillation. Thus, I conclude, it is reasonable to have an ablation when also using a pacemaker. I guess the pacemaker is there to keep your HR from falling too low, it will do nothing about any extra beats that come from the Flutter problem.
Good luck, let us know how it goes. We can always use current experience on ablation work for more questions that will continue to come in.