Can't believe yr Dr offered Prozac - it's not a cure all - anger is not a medical problem...
It might be worth your while lookin out for some self help books, and look at 'Mind over Mood' for good CBT (cognitive behavioural therapy) techniques -
http://mindovermood.com for more info, or look on Amazon etc...
I'm sure counselling would help you but sure there will be a long waiting list thru the NHS if you could get a Dr to refer you, or would be really expensive if you went privately.
Good luck with it - respect to you for admitting yr problems & trying to do something about it.