Hi OP, I've read your threads before. Quite a bit to unpick and not long to do it. So please take what I write here kindly as it is meant to be supportive and positive.
Firstly, I guess he needs to mourn the loss of his BSc at Lboro - it's not going to happen but that's OK. Most of us have had disappointments when things we wanted have moved forever out of our reach. So sorry if that sounds harsh but at least he is not in limbo for a year, reapplying and hoping and waiting. Equally tho it's OK to grieve for what he has lost (if that doesn't sound too dramatic). I asked DD who emphatically did not get the grades for Warwick four years ago and she says yes, she was really sad, and still feels that she missed something.
Next thing: RG. IMHO there is a lot too much weight put on RG here (not so much IRL tho). It's not the be-all and end-all. And in fact right now I think you might as well disregard it. DD (again!) ended up at non-RG Leicester and got an amazing degree and in many ways had a much better experience than if she had gone to her first choice.
Finally - "the best course" - hmmm I am deffo not sure that this is a thing. Most students I know (of) end up at xyz uni (first choice/insurance/clearing/where they could get in/where they had dreamed of) and actually are fine. If you're gonna like it, you will get on and enjoy it - at Bristol, Brunel or Brighton. If not, then not. Mate of DS's got in to Lboro (not sports science!) and hated it, left after about five weeks. Reapplied, Brum (funnily enough) - much bigger city, better opportunities for things to do, yadda yadda. How's he doing? Well DS says he will probably finish the course but he is not really loving it. Maybe uni just is not for him.
So what should your DS do? I think he should not take a place on a course just because it is nearby and handy and offering him a spot. He applied for this at UEA before I think and really didn't want it? So does he actually want it now? Maybe he also doesn't want Brum? He could take a year, do lots of coaching/training and work to rack up some money, and reapply with his great grades, looking at some of the places you have said he never considered - Lancaster, Sheff Hallam, Swansea? B in PE is no issue - I know plenty of people who have done SS with a B in PE and been successful.
By the way, he can still do this even if he sticks with Brum or accepts UEA for the moment. 4pm tomorrow to decide between them, but at least four weeks or more before he goes to either, and in that time he can back out and rethink.
I would ask him to take out the extraneous factors - girlfriend, commute, money-saving - and look at the course, the structure, the sporting offer. Can he see himself committing to either seriously for three years?
BTW (sorry long post!) I know it is controversial, but I am not sure that a year abroad is such a wonderful idea in general. I did one as part of a joint hons course and when I came back, I knew no one on the non-MFL half of my course. Unless everyone does a year abroad, I would think carefully about that. It sounds like a great opportunity but it was tough tough tough and very lonely for me. Just personal experience there for sure tho. And I guess with so much vastly improved comms it would be better now.