hi Julz! Welcome!
I'm also a big snacker, and it's taken me awhile to fine-tune my "plan of attack." I have a very similar problem- that darn afternoon hump/slouch type thing around 3 p.m.
My work day is 8:30-5:30. Around 7:15 I have b-fast, something high protein like egg beaters with some broccoli thrown in- and coffee (i can't get rid of that, try as i may!)
Around 11 I'm not really hungry, but starting to get there, and I'll have a small snack; lowfat yogurt, a few carrots with Laughing Cow cheese, maybe a piece of multigrain bread with some hummus or a tiny bit of peanut butter, with some fruit. (edit: i just re-read this, I don't eat all of this, just one thing and some fruit)
Then around 2 I'll have "lunch," which is more like a large snack; a veggie burger on a piece of multigrain bread topped with ff cheese, or maybe a salad with some turkey strips.
In between that I"ll have a warm drink- tea, once in awhile sugar free hot cocoa.... and fruit or veggies
Then I have another snack at 4 or 4:30 (if I don't I eat everything as soon as I get home!) and around 7 I have dinner.
Eating "mini-meals" has helped me from grazing on snacks all day long- knowing that I'm within a few hours of eating again and knowing what it is I'm going to eat has helped me tremendously.
I hate when people bring snacks to work and leave them out for everyone! The only thing I can do in that case is avoid the area entirely, or I"ll go nuts snacking.