Seems like your only restrictions will be how tired you are. Workout on the weekend if possible. and then try to squeeze in a workout during the work week.
if you really want to get down to it, you could try getting in some work on your lunch break but i have no clue how far your job is from your track. you could get in a good 20-30min of work with comfortable time to change and change back, I think.
That probably isn't feasible for you. So to tackle the issue of figuring out what will give you the most energy for your lifting right after work, i would suggest playing around with some high carb meals about 2 hours before your workout. Vary the amount of carbs and the timing, and find something that seems to work for you.
even if you don't have a strict plan for testing out the carb meals, if you happen to have a great day at the gym, write down everything you did/ate that day and the day before. try to repeat it, and see what caused it.