GCSE ISA biology help please?

ok, so I wasnt at school when my cl had done a practice for the practical part of the ISA for Biology. And so tomorow they are doing the written exam practice and we are doing the real thing next week. I am worried that because i wasnt here for the practical I might do bad on my real thing even though everybody said it was very easy. Does anybody know if it is really important to do the practice and what i should do because i am freaking out????? i am also worried that my teacher will yell at me or something as tomorow the whole cl will be doing the written exam practice and i cant. How important is the practice??? please help, will i be able to p still?????????