How do I go out and socialise on a weekend on my own?

I feel embarrassed asking this tbh but I'm autistic and even though I'm much better than I used to be I do struggle with initiating interactions. I'm staying in central London for the weekend as I'm going to All Points East tomorrow. I'm here on my own (nobody wanted to come 😞). I'd like to have a few drinks, not get pissed or go clubbing etc, have some food, and ideally meet some new people. Not really sure where to go or how to go about it though? Is this something people still do? I feel like I'd look weird going to a bar or something and sitting on my own on a Saturday night. Would just be nice to have a drink and chat to some people though, nowhere too loud or crowded. I've also only brought casual clothes. Vans and band t-shirts so I can't really go anywhere dressy. Any ideas/encouragement/reassurance appreciated.