For me, the LNAT was really difficult because it is impossible to gauge how well I have done on it. Although my marks in practice tests have been good and above average, my current worry is that I've done something wrong, misread a question or answer etc. The exam is relatively long and you'll have to manage your time well (at about 8 minutes per passage I believe). The essay was the worst part for me as I'm not the strongest essay writer. 1-1.5 months is reasonable as long as you are putting a lot of effort into it.