what should i take to the interview!

i've in a bit of a stupid situation!......i've got my sixth form interview tomorrow.......it's with the school i already go to......but on the slip they've sent me it says that i need my offer to sixth form letter they sent ages ago........but i kinda accidently threw that away!......and i have to take my recod of achievement....but i don't really have one i mean i've cetificates from middle school but only a few from this school!
wot shud i do!!!???

ring up and tell them uve lost the letter- they should say its ok. bring your record of achievement anyway