Need someone to sign a document so I can move but I don't know anyone, what do I do?

TLDR; Need someone not a family member (or the other person or their family) to sign a document so I can move, but I don't know anyone besides family anymore, what do I do?
Full version:
I'm supposed to be doing a mutual exchange in less than two weeks' time, but my housing association just asked me to provide a witness to countersign a document before I can move. They can't be a family member, the person I'm swapping houses with or a family member of theirs.
The thing is though (and I know this is tragic lol) I don't really have any friends anymore (I moved here a few years ago and stupidly never made an effort to meet anyone other than my now-ex partner). My old friends from where I used to live won't do it (basically they were disgusting chavs and I told them so haha), neither will my ex (who presumably would've been considered family anyway). Besides family (who like I say can't do it) that's all the people I know 😂😭.
I seriously doubt my neighbours (who we never spoke to and vice versa) or people from down the pub would do it either and I'd rather die than ask lol. I didn't work so no colleagues to ask. Plus I'm studying online so yeah, no one there. Can I just get a family member to do it or will they find out? Like for example my mother has the same surname as me so that'd be obvious, but my sister doesn't, how would they know she's family?
Or could I just give a random name/email address/address? That's what they've asked for so far. Are they actually going to speak to this person/check them out or what? Surely that'd be too easy haha.
I'm sure I'll find someone who can do it but I'm really worrying I won't be able to swap now and I'll be stuck here forever, I hate it. The person I'm swapping with must have someone who can do it but knowing my luck probably not lol. Really overthinking and worrying as I'm stoned af rn 😂.
Also doubt anyone will lol but if anyone here would kindly do it I'd pay, not a huge amount as I'm already broke af from having to pay rent in advance and stuff (plus it's only a signature/quick filling in of a form), but yeah.