There is little of value you can learn at home before your IR course. There is however quite a lot you CAN do at home once you are into your course. Armchair flying can save you a lot of training time (and of course cost) on your IR. Practice checks, emergency drills, GPS/approach procedures, RT, speeds/power settings and review plates at home - costs nothing. If you have some software on your PC that can replicate your IR training, all the better. Practice, practice, practice - twin IR training is pushing £10/minute and you don't want to be spending that time learning EFATO drills or the like. Don't turn up for a lesson without adequate preparation. PPPPPP.