For any new UK users to Lemmy, consider making an account over at Feddit.uk. It’s an growing instance with a specific community focus on all things UK!
I’m not a admin of that instance, but made my own account after Lemmy.ml became too slow to use and the difference is night and day, at the time of writing.
I just went straight to Feddit.UK after reading that it was best to choose small, but not too small instances. And yeah, it's been great. The only issue I've found is that joining communities from other instances can be slow - I assume that if you're the first subscribers on your instance it has to do some fetching of data. Yesterday it took me 10-15 minutes to join one community.
Clicking on these causes Jerboa to crap out for me. But as someone else pointed out if I click on community links via another users profile it takes me to the community where I can subscribe, even if it's in another instance.