I'm afraid I diagnose the condition as being Maturestudenttakingthemselveswaytooseriously. All about the work, no mates, long journey and "stressed and unhappy". If you're going to carry on like that, you might as well give up now and save yourself the pain of completely melting down in about 14 months time.
It's a bit late to do much about it now, but I suppose it depends on your motivations, what you're reading and why.
It sounds to me like you are (figuratively) on a degree course, but you're not at university. You're experiencing only the education and work, and nothing else.
To deal with the issues one at a time:
1. No mates - this is inevitable. You freely admit that you don't relate to the kids. You possibly come across to them as the un-fun mature student that they don't want to be near, or even worse, as one of their parents. If you don't want to completely crash and burn; this has got to change. You are going to have to work at it as well and have to make time. It doesn't matter if you think the socs are aimed at kids - you have to make the effort. There is a zero chance that someone half your age is magically going to sidle up to you and be your friend. You have just got to join a couple of socs, visit them and narrow it down to one that you think you might enjoy and make time for it. I know people who have literally been suicidal after a bad start at university and have been saved by being a part of a club or soc. Get on some socials, and attend them. It will probably be inconvenient - but if you want to meet people, that's how it goes. It might be something awful like Scifi club or baking - but as long as you think you'll half enjoy it.
Maybe concurrently, it might be possible to reconnect with the kids on your course. Try to get yourself on a course social, or if you are particulalry thick-skinned, organise one yourself (at the risk of no-one coming). You got to at least show willingness to try and relate to people.
2. All about the work. Well, that sucks. Do you really need to do all that work? Will you fail if you cut back a bit?
3. Always stressed / unhappy & partner cross. Like in Frozen, let it go. Try and fix the other things and get to the point where you are enjoying university rather than withstanding your course.
4. Long journey. Yeah, sorry. Nothing that can be done about that.