The best idea is to spend time studying and researching which bands certain universities expect. This will provide you with something to aim for and a rough idea of where you think you could apply and easily get in to. Different courses will also require different bands, too. If you are applying for more expensive and respected courses, such as law, you will be expected to have a minimum band score of seven or higher to understand the advanced terminology in course literature effortlessly.
So: The minimum IELTS band required to study in UK universities ranges dramatically. Advice would be to make sure that you know what sort of courses and universities expect when you are applying to study with them. You will find that many of the universities will be keen to take you on in order to give you the opportunity to study with them, so as long as you can impress with a score of around six or seven you are in a comfortable position. Alternatively, if you are aiming to score as high as eight then you can look at the big universities.