If you feel like there's a language or culture barrier, ask if there's any society for people in the same situation! I don't know how common Austrian societies are but uni is scary enough for people who are from the UK so I imagine starting uni AND coming to a new country is pretty terrifying! Go you for actually following through and making it this far though.
Even if there are no societies for international students, you could always join something that simply interests you. Most unis have loads to offer.
And you think your bed is bad? My matress was so thin I could feel the metal bars of the bedframe digging into my ribs and hips and I got bruises from it! My room was also away from everyone elses so I was quite isolated. The only saving grace is that I didn't have bars on my window (no joke, I knew people that did).
As for friends, you're only a few days in. You haven't even started your course properly yet. I didn't really get on with anyone in my block in first year but I did meet people I got on with on my course. You have to put yourself out there a bit though, go and say hi to people. They won't always come and say hi to you because they're just as nervous and unsure!! You'll meet people who won't be into the same things as you but there's so many people at uni there WILL be someone with common interests. I know how lonely it can be, as do a lot of people on here. You're not alone.
Don't worry about your 'knackered' comment. I don't think anyway will have taken too much from it, besides it wouldn't be surprising if moving to the UK from Austria to start a new life WAS pretty tiring! Why didn't you go out of the common room area and ask where they were going? People won't always just automatically invite you I'm afraid.
Don't worry about not drinking, I don't drink and know quite a few people that don't. I've never been pressured to do something I don't want to whilst at uni.
The best thing about the first few weeks (besides not much work) is that you can approach people and talk to them without them thinking 'why's this random guy talking to me?'. Use that time to your advantage! Don't worry about seeming too friendly or weird, people meet so many people in the first few weeks that they've forgotten most people who they didn't stay friends with. Try not to overreact or do anything rash whilst you're still in early stages with high emotions.
It's normal to feel lonely and unsure at the start. But if it goes on for more than a month, go and talk to your tutor. Then you've had a little longer to see if things get better, you'll know how much you like the course, other aspects of student life, etc. and you can weigh up if your experience is good or bad and decide what to do from there