You mention the possibility of Cardiff. According to the NCTJ website, Cardiff don't offer first degrees in journalism. They only offer a post-graduate course.
Your son should look into the courses offered by Bournemouth, Edge Hill (Ormskirk), Liverpool John Moores, Southampton Solent, Staffordshire, Central Lancashire, Portsmouth, Salford, Sunderland and Teesside:
http://www.nctj.com/course_introduction.php
From those, I'd put Southampton towards the top of any list, simply because it's such a vibrant city for student life.
(if your son is absolutely certain that he wants to go into sports journalism, he might want to check the specialist course at Brighton, which is a wonderful city for young people).
Lastly, although qualifications can help to get a job in journalism, he'll only make progress if his writing is good enough. (Even those who end up in radio or TV studios often start in print journalism). If he's not already started to submit work for publication, it's definitely time he started. (I wrote my first sports report, for a local newspaper, at the age of 14. Over the years I've had quite a lot published, both in newspapers and magazines. I didn't bother getting any qualifications until I was in my forties. They've not made any difference to the amount of writing I get published. Ultimately, it's quality that counts).
Chris