Hey, I'm UK based and I actually have a fair bit of experience at various events.
Advice-wise... err... other than like obvious things like "bring a bottle of water" and "have a buddy to mind your table if you need the loo"...
Each UK event has a different vibe.
- MCM is the biggest, but people with more indie styles may struggle there because a lot of people go for shiny fandom stuff and the punters skew younger than other events. If you have work with broad popular appeal though you can make an absolute killing because there are so many people.
- Thoughtbubble is one of the best for selling indie comics. It's a pain in the arse to get to if you don't live in Yorkshire, but it's worth it. Probably my personal favourite event.
- LICAF (Lakes International Comic Art Festival) I have some...er.... personal history with but I'll try to be objective. Really I'd only recommend LICAF if you're a very artsy sort of creator (ie. you love Nobrow) and also you fancied a trip to beautiful Cumbria outside of tourist season.
If you're at an event, make friends with everyone! The UK scene is small and cosy and having friends goes a long way! Some cool people you might meet at UK events with comics on Tapas might include the creators of these comics:
I can vouch that all these people are incredibly nice, friendly and encouraging! I've known them for years. You might also want to look out for Kate Ashwin (makes a webcomic called Widdershins) and Naniiebim (makes various cool comics and fandom things). There are tons of creators out there who are also fun and chill, so just be nice and humble.
Maybe at some point I'll be on a table again myself, but this year I'm just going to TBubs (thoughtbubble) for fun. My comic is:
