I was a PT student my first year and worked. (Although PT at GULC just means one less class- it's still 12 hrs)
I would never ever do that again. I was pretty much a walking zombie the whole year, addicted to coffee, etc. 1L year is bad enough without work to worry about. Perhaps it would be more sane 3L year.
Those of us that are PT students and have full-time careers do it every year. Suck it up and take the job. Are you seriously whining about 12-18 hours a week OP? PT students take ONE less class than you do and work 40 hours a week.