Man, you should go get yourself ready !
Battlefield 3 Premium @Virgin is for 25$ only (for PC)
I bought one since i first saw it on sale, and i dont even have my Gaming PC yet !
You should go get it, i got premium for PS3 for 60$ ! PC is 25$, GO GET IT! That is if its not already sold out.
Gaming Battlefield 3 on a laptop ?! It better be a one hell of a laptop man !
Now how to actually play the game online,
Well first, you have to buy the game of course, you can get it @PcandParts (like i did)
You should also have
Origin installed on your PC, that is where you are going to redeem all the online passes and/or DLC pack codes or premium codes etc... and you can download them all from Origin.
Hope i helped.