Opportunities to sit the gamsat

[uoping]

As a first year student, I have 4 possible opportunities to sit the GAMSAT before my undergrad degree finishes. One of them is in September of my first year (GAMSAT UK). Can this score be used for entry into postgrad med or do people do it purely for practice purposes? If not, what about the UK GAMSAT that you can sit in the second year September?
Also, do they take your best score out of all your attempts or just your latest one?

Thanks.