It'll be interesting to hear your experiences here as a newcomer and compare them to how it was a year ago when I suspect is when most people joined.

If you haven't done so already, have a 2 minute read up on how federation and the fediverse works. It sounds a bit complex to start with but it's basically just a bunch of servers that all talk to each other (like how if you're on gmail you can send an email to someone on outlook even though it's a different server).

As for feddit.uk, I think it's generally got a pretty good Casual UK sort of feel. You'll find that some instances take things very seriously or have power-tripping mods, this one seems to generally be pretty chill!

The main different compared to reddit is that it's much smaller here. Don't expect an active community for every niche interest, and don't expect thousands of new posts every day. Due to how federation works you might need to use external tools to find stuff, for instance lemmyverse search to find few communities.

Ultimately it is what you make of it. Find the stuff you like, ignore the stuff you don't, and post the stuff you want to see more of!

I suppose it depends on what you mean by "this place" as the Fediverse can make that a trickier question.

On feddit.uk, the instance you are registered with and the host of this community (and as an Admin I may be biased), it's relatively relaxed. I signed up here because I figured I'd get a good mix of UK news and posts with a UK slant (on the English-language Internet things often default to a US perspective), as well as folks with a more... British sense of humour and that's pretty much worked out.

On Reddit they tend to consider subs to be the Mods personal fiefdom (unless they shut them down in protest) and that concept has carried over to the way some instances run things (it's often difficult to replace Mods on some communities even if they've been MIA for a while). However, I've been part of (and often ended up helping run) online communities since Usenet and my take is that it's everyone's Instance, the Mods and Admins are just here to make sure everything runs smoothly and the lights stay on. I'm happy to let Mods deal with the reports on their communities (as most are that posts and comments don't fit the remit of the community) but if a Mod is inactive for a while or there is evidence of power-tripping (the latter hasn't happened yet) then they will get replaced.

Further afield in the Lemmyverse, you'll find a range of instances that cover different topics or serve different communities and the way things are run can vary from orderly to pretty freewheeling and chaotic. You'll pick all that up as you go along but don't be afraid to block instances. Otherwise the best way to organise your reading is a mix of Local and Subscribed. On feddit.uk, Local is pretty manageable, on larger instances it can be a firehose of content (with a lot of Linux memes and shitposting). Subscribed let's you pick what content from around the Threadiverse you want to see. However, don't expect the same breadth and depth of communities as Reddit has and, a lot of the time, you can't just be a passive consumer of content (or you can but don't complain about it) as there aren't enough people here yet to populate niche communities with a steady flow of interesting material. So get stuck in, it'll be a lot more enjoyable for everyone.

And if you have any questions feel free to ask.

Aside from the points made so far:

Expect it to be overwhelmingly very left-wing and radically progressive on social values.

You will get downvoted for expressing opposing or even skeptical opinions, often brutally. It doesn't really matter, Lemmy's 'Karma' system doesn't work like Reddit's does, but just expect that.

My account is like 12 hours old but I was trying out Lemmy on other servers well over a year ago. Nothing about that has changed.

You might feel similarly to the majority and therefore you'll have no problem.

If you don't, eh, well. There we both are.

Also, yeah, post links and create subreddits about stuff you care about. These sorts of alternatives only live if people engage with them.