First up is to remember this: "What I put in my mouth will not change the way I feel"

And then, yeah, substitution is good to a point, but once a week, actually treat yourself. So, for example, have a 99% fat free hot chocolate for 6 days of the week, but then on Thursdays (or whenever) have some real chocolate. Buy the best stuff you can, and make it really special. Then you can look forward to it all week, and it is your true reward for making it through.

Heaps of good substitutions:
(this is how I started out 20kg ago. Now it's a whole different story and I have wiped these habits out completely)
chips = rice crackers (seaweed was my vice)
salted nuts (count them out into a little bowl and then put the packet away.
celery sticks with a delicious dip (I now make all my own)
corn thins with vegemite
chocolate = low fat hot choc (esp in Tassie with your delicious cool weather!)
low fat flavoured milk
ice cream = yoghurt type thingies
lollies = dried apricots and dates

Sounds like you're well on your way! Good luck, love! You can do it!