None of your choices are 'top' Unis for Law. Birkbeck is an evening Uni designed for mostly for mature students. Brunel focusses on STEM subjects. Roehampton's focus is Humanities and Teaching. There's nothing wrong with the Unis you have chosen, just that they are not 'known' for Law. You'll probably be able to get a perfectly good job with a Law degree from one of them, not necessarily in Law, but you wont be in the picture for opportunities at top London Law firms.