I have flown flaps and I am a full scale A&P most everything I work on and flown 40 deg flaps is max. To use 40 flaps you're heavy and on a short runway. Flaps down increases lift but it also I creases drag.
The advice given so far is spot on. Practice up high including stalls so you'll know how the plane will react.
Plus I don't recommend waiting until final to put flaps down. Deploy flaps on the down wind leg.
Sorry for the loss good flyin to you