Hmmmm. First of all OP you may have got a different set of responses if you'd posted in the Higher Education section - "Further Education" tends to be FE Colleges etc. There are some very expert academics posting in the HE section who may not have seen this pthread.
But anyway ...
Your opening post is quite a jumble of lots of stuff. It feels as though you're absorbing your DS's panic & upset, and replaying it in your own reactions.
My first thought is that maybe your DS is not ready for university.
My second thought is that you (or him?) don't say anything much about how he's enjoying (or not) his actual course.
There's a lot of projection of his own shyness onto others. It's verging on a kind of xenophobia to attribute part of his problem to overseas students. They are obviously hugely clever to get to the place your DS is at (either Imperial or LSE from your 1st post?) in another language and totally different culture. I'd say their "cliqueyness" is shyness and anxiety not to offend.
If it's your DS's shyness which is making him suicidal, then he really really needs to seek help. CBT or some other coping therapy is necessary. I remember being paralysingly shy when I started university - I was 18 months younger than most, and had rarely caught a bus before I moved from rural isolation to a big city university.
But I got over it. I womanned up - I grew up, and I found ways of learning how to deal with my shyness. As a young woman at university 30 years ago, I also had to learn to really speak up - I didn't have any privilege of masculinity (or height or good looks) as your DS has.
What are his interests? Can he join a club or society - again, it'll be hard at first, but he'll meet a couple of people like him.
But the bottom line really is - wherever he goes, he takes himself with him. A move to Newcastle (excellent city, excellent university) won't suddenly cure his shyness. And what if his girlfriend dumps him?
Can he get involved in other aspects of his hall of residence? There's usually a Dean of students & sub-deans resident in London halls (especially LSE ones) - they'll have seen it all before. He could talk to one of these senior residents confidentially. They might be able to introduce him to other students. In my experience of years of freshers, they very rarely only socialise with their flat, kitchen or corridor. There will have been lots of stuff put on in Freshers Week for just this purpose - to get people mixing.
I'm afraid I think your son is projecting his own fears, anxieties and fear of failure onto other things. BUt if he's been brought up with such an all-or-nothing view: top 3 in the world for his course, or something. Anyway, a degree from here would set him up for life career wise from you and/or his father, then no wonder he's so anxious.
Maybe he needs to take another year out from university - he really needs to find a way to overcome his pathological shyness.
I'm trying to be helpful here, although you'll probably read my whole post as harsh and nasty as you have reprimanded deckoff - whose advice is tough but sensible. I'm trying to give you the benefit of the doubt, but there are some nasty goady things in your first post about other students, and then we get this in a subsequent post about Chinese students:
They go home with an English degree which is very prestigious, the English uni gets pots of money. It is a scandal and will eventually be exposed by a budding journalist one day.
You're upset for your son, but this is just goady racism, and both you & he are using it as an excuse for his unhappiness from the sounds of it. I've taught a lot of Chinese students over the years - and I am in awe of them. They cope not just in a language but a whole bloody alphabet that is very very different from their own native languages (most Chinese students speak at least 2 usually 3 languages before English); they are undertaking an expensive education in a culture and educational culture also totally different from their own. The Chinese students I teach are extremely bright, very motivated, and work insanely hard - and are quite a lot of fun, once you can get into a bit of sympathy with them - but they are deferential and shy because they are afraid of losing face, saying the wrong thing, or offending. I love teaching them - and I hope they go back to China with just a little bit of an understanding of the chaos and creativity of the West - and value it.
And the huge fees they pay are subsidising your DS, don't forget.
I think you need to stop projecting onto your son, and enabling his shyness.