Hi, I am sure many of you will have checked the UK sites as well as Boards,ie but here are the thoughts about the different preparation materials of a UK poster who got 76 and 82 in Gamsat!! The student room will give you UK insights.
There are many different ways to prepare for the exam, different methods will work for different people... Although that poster earned a fantastic score, I don't think it matters much once you get a high enough score to secure a place.
Yes I suppose it depends on your background and whether you have Science or not as to your needs. Common theme appears to be practice.