Yeh my diet is terrible, usually a sandwhich, bag of crips and a mars bar.
I dont eat fruit or veg, well very rarely and drink a lot of tea and coffee
I also dont exercise anymore
so yeh, its kind of obvious really
I think you've answered your own question!
If this is a genuine problem for you then why don't you just make a few changes.
At lunchtime have some fruit instead of your usual lunch. Bananas, apples, oranges, whatever you fancy.
Don't try and fill yourself up, just eat some fruit...your body will adapt and you won't fill hungry.
Try joining an exercise club (I know difficult at the moment) and I would recommend boxing.
You'll make some new friends (and they'll beat the crap out of you) but you'll feel like a million dollars (or about £750,000).
Eat fruit, go boxing.
Trust me