Have your GP write you a prescription for generic Proscar, it is much less expensive than the actual brand Propecia and both are still the very exact medication, which is Finasteride. Proscar comes in 5 milligram tablets of Finasteride, and yes, cut the tablets into four pieces each, and take 1.25 milligrams of the medication daily to treat genetic hair loss.
Just a suggestion, I recommend that you see a specialist, which would be a hair transplant surgeon. They are much more knowledgeable about hair loss than a general practitioner.