The lid is closed. How can I tell if my Macbook Pro M2 is in sleep mode or shut down?

Hello NneteenUK,

Thanks for reaching out to Apple Support Communities. We see you have a question about the lid being closed on your Mac and staying asleep, and we'd like to help. Changing the shut down settings may be the best route to look into how your Mac goes to sleep: Set sleep and wake settings for your Mac - Apple Support

Specify sleep and wake settings for a Mac laptop

1. On your Mac, choose Apple menu  > System Settings, then click Energy Saver  in the sidebar. (You may need to scroll down.)

2. Do any of the following: 

* Put hard disks to sleep: Turn on “Put hard disks to sleep when possible” on the right.

* Update your system while it’s asleep: Turn on Enable Power Nap on the right.

* See What is Power Nap?

* Allow your Mac to wake briefly so users can access shared services (if applicable): Turn on “Wake for network access” on the right.

* See Share your Mac resources when it’s in sleep.

Let us know if this helps.

Regards.

If the charge is at least 40%, just shut it down. I say 40% because when you get back you'll want some state of charge.

You can shut the Mac down any time you want and be safe. Just don't allow the battery to become completely exhausted. You can also leave it "on charge" for extended periods with no harm with it's running, sleeping or shut down.