i just saw your post, sorry for late, visit of ganga choti was awsome experience, as you mentioned 6 hour travel from islamabad directly to ganga choti, this thing was in my mind, so i planned my trip to go to banjosa end stayed 1 night at banjosa lake, 4 hour travelling distance from islamabad, and then next day travelled to ganga choti from banjosa 3 hour travel. 2 km before ganga choti it is sudhan gali, we stayed in tourist lodges, they have very beautiful huts over there with wide lawn with view of mountains.. prior booking is required 2 days before visit, but luckily i got on spot booking just because a family cancelled there booking and got 1 hut with two bedroom 1 kitchen, electric gyeser installed n working.
you can reserve only 1 bedroom as well.
you can skip banjosa from trip, it is not worth visiting 