I dont really know what the LNAT is, how can I prep for it?

The most useful tool when preparing for an LNAT is practice papers and the LNAT website itself. The more practice essays you write and get feedback on the better your essay form will become. Often the actual content of your argument in the essay is immaterial, it is the conviction and form with which you write that the examiner is looking at. The LNAT isn't a test like most you will have sat in your education, it is not about right or wrong answers - instead it looks at the way you think in a critical manner. Articles that assess the nature of critical thinking can also be extensively useful in the run up to sitting the exam, and recommendations of such are made on the LNAT website. Personally, I found one of the most important points was to get used to sitting in a room surrounded by other people and concentrating at the same time - LNAT testing centres are full of people doing all different kinds of tests, leaving at random moments and definitely aren't as calm as the average examination hall you will have experienced so try doing practice papers in the busiest room of your house and gain experience in zoning everything out and focusing your attention.