I would agree with RooDog.
RPL seems similar in many ways to the old Restricted Licence (that was in place before the GFPT idea replaced it) and I think has a valid place.
NB You don't have to obtain an RPL on your way to a PPL, you can skip the RPL flight test and just keep training for the higher licence if you want to avoid paying for it.
I also would be surprised that a decent school who trained you to obtain an RPL would not allow you to hire one of their aircraft.