congrats that you have made your mind about CAT, now next imp thing is to remain focussed and not the drop mission CAT in the middle.
now regarding preparation for CAT from home, first make a schedule which you shall follow and rule no 1 shud be that you shall be ready to study any time any where, i.e mug vocab when u r not doing tables and do tables when u walking ...
so have a regime
second i sbuy some second hand notes of IMS they r good, and u will get them at classifieds sections here only. and also get books by R.S aggrawal etc. at the same time read ET/ Business Standard to get a feel of currrent sceanrio it will help you in GD/PI
for CAT 3 hours of regular study is sufficient and also take good breaks as in CAT preparation a lot of students burn out by the time they appear for CAT
so plan your work and then work your plan and you will ber belling the cat fast