what are the main courses that one is required to take inorder to do his/her undergraduate in finance?

You will need to take the basic core classes (english, college algebra, science, social studies, etc) and then take the classes for your major which will include math, statistics, accounting, etc. In order to determine exactly what classes you will need, contact the school you are interested in attending or look them up on line and look in their catalog to see what they require as different schools have different requirements.

Probably maths (minimum grade C at GCSE), business studies, economics. some of those few subjects that involve numbers