I see you've asked the same question again about its competitiveness. I mean if you've got the grades go for it, If you get rejected it's not the end of the world as you have four other options. Although I don't know about computer systems engineering but I've been seeing some Comp Sci rejections of people with 4 A levels at A*s ish. Although Cs/e might be a little less competitive as it's a bit less well known. At this point you probably can't change your grades but if you're considering Warwick you should already have the grades. Just make sure your personal statement is good.