Which uni to select?Watch
Do you think you want to do a PhD and if so do you know what area you want to do it in? If so, pick the Uni that has the faculty staff most aligned to your interest as building a decent relationship with a professor / assistant professor is a good way to progress to a post-grad funded research or to be offered a PhD place within the department.
Are you extrovert and is part of the reason for studying in the UK to integrate and mix in addition to getting an MSc from a UK Uni, do you want nightlife and clubbing? If so, look at Sussex due to being on the edge of Brighton (great pub and club scenes for all tastes) and the ease of getting to London.
You get the idea, but having some idea of what you're looking for from your Uni experience and living in the UK experience will help others make recommendations based on their knowledge of these places.