@BuFord you'll probably be a reasonable beginner then. My experience is the more incompetent a beginner is, the less they realise it. 🤣
Personal favourite was the total (lady) beginner who turned up at men's first team practice and wanted to join in because she was "very good" and she thought they'd be "about the right level for her". They good-naturally gave her a set in which I don't think she got a ball over the net and in.
At the end when they asked her to let them continue their practice she had a massive strop and ended off walking off shouting over her shoulder "just because my game was showing you up..." Five years later she still had the same attitude and not a much better game either. People used to leave the club by the back route when they saw her walking up with racquet in hand. 🤣
A close second was a match I played in, where the opposing team had initially told us that they might be one short, but when we turned up they were jubilant that they'd got a new member who'd told them she was an experienced team player, and they were almost apologising that they thought she might be a lot better than the rest of us.
I'm not sure what sport she was experienced in, but it certainly wasn't tennis. I think we lost 2 points in 2 sets against her and her partner, and one of those was a double fault. We weren't even playing that hard because we were feeling a bit sorry for her partner, but she was determined to poach even when it was well out of reach.
At the end we left her cheerfully saying to the captain, "I'm on for the next match. I've got it in my diary."
On the basis they were a pretty good team and went up that season I assume someone was able to disillusion her.
After those two you can go in confident you won't make a fool of yourself!
My suggestion would be, get yourself a few lessons. Group is fine at beginner level, but you will learn quicker at 1-2-1. See what the relative cost is. I was horrified to find that our club charges roughly half the cost of a private lesson to the groups (talking about 10+ players) and you definitely get far less than half the benefit, I'd say probably less than 10% for that number of players.
Get a nice racquet. It will make a difference. I'm still playing with my 1990s vintage racquet because I love it. But when I bought it I tried a few. You want to make sure it's comfortable in both weight and grip.
Buy yourself some balls. You don't want the 3 for 99p level balls. You get sponge puddings better to play with than those. Especially my Gran's...
I'd go for 2-3 tubs (with a ring pull top), and dry them out if they get wet. Don't get tretorn if they're still trading. Odd balls, they actually bounced more as they got more threadbare than the other way round. I'm sure they were actually aliens balls.
Then between lessons give yourself a practice. Whether that's a tennis wall at the club (we have one - it's fantastic to lean on), wall at your house, or if you can't do either, then even just sending a ball across the garden helps, or failing that bouncing the ball on the racquet. If you have a friendly child/partner/friend then put the balls in a bucket and they throw them to you and you hit them over the net back.
Or if you have a long drive (and no local free ranging dogs) you can use one of these:
Buy Tretorn Tennis Training Device Blue online | Tennis Point UK (tennis-point.co.uk)
Yes, it is tretorn, but the ball not decaying is an advantage because attaching another is a feat I never worked out how to do. This was how I learnt.
Do something between 10 minutes a day and 30-60 minutes twice a week. You will improve. Focus on getting back at first rather than perfect technique. If you can get your rhythm for playing then the technique can come later.
Once you can do ground shots, try serving. You can go down to the club with your bucket of balls and just serve endlessly. Practice is the main thing here.
When you can serve then you will almost certainly be fine at the club sessions. I would advise getting down towards the beginning, but not at the beginning, and only doing a couple of sets/whatever you play, at first. People are far happier to play and encourage a beginner if they don't feel that they're going to be playing every set with you especially in a small club.
Other thing to look at is court surface. Almost no clubs unless they're really posh have decent grass courts, but I'd go for either hard or artificial clay. We got artificial clay a couple of years ago and I love it except for when I get bits in my shoe. I'd avoid astroturf (slippy in the rain) or carpet (never seen one that doesn't puddle like a bath in the rain and doesn't drain, so you get showered every time the ball lands even once it's stopped raining. Indoor is okay. Don't like it myself, but it definitely has advantages, especially in the wind.
And enjoy it. It's a great fun game!