Bilbob,
I have just completed all ATPL's(Today incidentally-pending pass of last 7). I have a full time job, including the occasional night duty.
It is extremely feasible to continue working right up to the exams providing you are committed and disciplined. It IS hard work-it IS frustrating but it can be done, indeed at the expense of your sanity! If I had the choice(ie.the financial liberty) I would take maybe two weeks off for each module. Get up at 8am like its a regular working day and regulate yourself with coffee breaks etc.
Vis-a-Vis the actual study itself: Study the notes provided by your groundschool FIRST, assimilate the information. THEN tackle questions-suggest Bristol Questions. Do not learn banks of questions without the knowledge - however, the questions themselves do teach you alot and generally drum home the most salient points.
Good luck with the GS and remember: you always remember what you dont think you will!
Walk the line