I second the cranberry juice, and start taking the cranberry capsules on a regular basis. Also get acidophilus in chemist - builds up your good bacteria, especially when on antibiotics, stop thrush developing (oh the joys of been a woman
Panadol you can definitely take. They will do no harm at all, in fact until antibiotics work they will ensure your temperature stays nice and normal and they will help a little with the pain.
As you say drink a good bit, but space it out evenly as much as you can over the day, so you are not overly filling your bladder in one hour.