OH. Pleas don't do study abroad to "make up for your grades", do it because you want to and that you love the culture (which is what I'm gathering anyway :P) Just I want to make sure that you don't get stuck in England miserable for a year. Also, very likely, your GPA could drop in England, especially since you'd be spending one of your most challenging times in England, in a place away from what you are used to. I'm not saying it's a bad idea, just make sure you are going for the right reasons.
(I was thinking about a year abroad too, but I started thinking more about going during college.)