As someone who did really bad in my contract law (was a first year module during my LLB) I've been told my some specific recruiters that it's not an issue because other grades were higher. If it was purely about the grades they'd already have that benchmark set. Don't let it dissuade you from pursuing TC's or a career in law. If anything, having a spread of different grades in different areas says interesting things about you. Contract law is hard, yes, it's important too but you've shown that you excel in different areas. Don't let it put you off imho.