yep, what everyone else has said, you can use them for 1 paper iirc, and you really dont need them for that ( the only useful thing they do is solve simultaneous equations, but that isnt hard, its just dull)
Get a scientific one and rejoice in your newfound knwoledge of maths, that said, i have a casio fx9750g that does everything ive ever needed for a level maths and further maths and all through a theroetical physics course. the motto being, get a cheap one, if your teacher reckons you need one, get the school to put a bulk order in and buy them from them