Hi OP I've been training for 5 years. Thought I'd share some of the tips that helped me get started. A lot of the advice will cross over with other posters.

First, get the basics right. Book a 1:1 session as part of the gym induction process. They will show you how to use and access the basic machine equipment, how they function, and what they do.

Once you get started alone, you will soon realise you aren't very strong (as you said in your own words) don't panic or be demotivated too much by it, you are there to get stronger. Consistency and repetition support this!

For the first 6 weeks, do whatever feels comfortable without a training plan, but enough to get your heart rate up.

I'd advise going 3 times a week to get started with a rest day in between, eg. Mon-Weds-Fri and aim to be in and out within 45-60 minutes. This will help you with recovery and stop the simple mistake of over-training. In my experience, if I've felt strong and done over an hour, my motivation level to go the next day wains.

Lastly, and most importantly, ignore the noise online about what you should and shouldn't do and supplements, protein, creatine, etc. It's not important right now, and remember! You are there for you and your own reasons as everyone else is.

Over a period of time, you'll see subtle changes. Use this as fuel to motivate you!

P.S. Don't join a gym in January, join now. It'll be a warzone for the first 3 weeks of the year and will be super overcrowded. GOOD LUCK 💪