Science

The eligibility for PG Diploma is graduate in any stream.

No it is not difficult, it depends on your interest.

It differs according to the college for example presidency college allow the students for bsc in geography those who have economics or maths in 11th and 12th classes but some colleges allow geo bsc hons for not having eco or maths in 12 . But if you want to take bsc you have to take eco or maths or else u will get ba hons in geography. I will suggest u to take economics as maths is harder than economics to getting bsc degree in geography

Just do not worry about your lack of liking for mathematics. It's not a subject that is of vital importance in life. You can definitely do your graduation in Science without taking mathematics as a subject. You can do specialisation say in zoology or botany or microbiology more. There are plenty more subjects. Just keep your eyes and ears open and a whole new world about mathematics will appear in front of you. Best wishes to you.