One piece of advice. Make sure the pinch hitter instructor recognizes the difference between teaching for a PPL and for a PH.
In a medical emergency a PH needs to be able to talk with ATC on the radio, read the compass/DG/GPS, use them to follow vector instructions, fly level, do turns, climb, descend, and fly a straight in approach to a runway that is selected to be into the wind, 6000-11000 ft long and 100-150 ft wide, and land.
All but the approach and landing are pretty standard PPL stuff, and any instructor will teach them pretty much the same way to a new student. But the landing is much different. Standard practice for the PPL is landing out of a standard tight GA pattern into a runway maybe 40 ft wide, 3000 ft long, and seemingly has a crosswind every day. If you have an instructor who can't (or won't) recognize the difference between the much easier landing requirement for a PH and the more challenging standard for a PPL, it is easy for the PH student to struggle so much with landing that they get frustrated and stop the PH training before accomplishing that key last step.