Domestic league tables are very volatile so you shouldn't expect any accuracy from them, however they can be used broadly. Ultimately between places like UEA, Kent and Newcastle the difference in terms of employment opportunities will be negligible. For normal grad jobs/schemes the employer will look at your degree grade, your work experience and extracurricular activities when making an interview offer. They won't reject you solely because you went to Kent and not Newcastle or reverse.
As much as the student room obsesses over university prestige, unless you're applying for a job which puts you in the top 10% of salaries - university ranking is more of an egotistical thing. Go wherever you're happy, if it's because the university has high entry requirements, a higher position on some league table or because you like the course structure, so be it