I recently completed my atpl whilst working 7 days a week, 8-6 in a retail head office mon-fri (pretty stressful) and then doing a 12 hr shift on sat and sun in a warehouse. I managed a 94% pass mark and I am no brainiac.
It is hard, it was life consuming for 18 months, didn't go out, studied every night till 10 ish, working til 12 in run up to exams, felt like a zombie at times, but boy did it feel good when I finished them all.
Good luck