sis i'm not doin med, but i can tell you in London it's a competative study. First you have to get the grades, then you have to pass the test they make you do, pre-med test i think.
On top of that i think its also important to pass the interview stage, leaving a good impression hopefully. they must see your zeal and enthusiasm reflecting on you (that's what i've been told).
But teh biggets of them all is how strongly you want it yourself. I think you have to have a burning passion for medecine in order too make it to the end, it's not easy dealing with it for the sake of it. I would say sis, make sure you ask the different med schools what they require, because some can get picky about small stuff. Make sure you've got all the info.
Anyways i pray Allah makes things easier for you nd every1 who wants to do med. InshAllah.